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Implement and document the llvm.eh.resume intrinsic, which is
transformed by the inliner into a branch to the enclosing landing pad (when inlined through an invoke). If not so optimized, it is lowered DWARF EH preparation into a call to _Unwind_Resume (or _Unwind_SjLj_Resume as appropriate). Its chief advantage is that it takes both the exception value and the selector value as arguments, meaning that there is zero effort in recovering these; however, the frontend is required to pass these down, which is not actually particularly difficult. Also document the behavior of landing pads a bit better, and make it clearer that it's okay that personality functions don't always land at landing pads. This is just a fact of life. Don't write optimizations that rely on pushing things over an unwind edge. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132253 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
John McCall
parent
bd0fa4c00d
commit
d7c1086201
@ -35,6 +35,7 @@
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<ol>
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<li><a href="#llvm_eh_exception"><tt>llvm.eh.exception</tt></a></li>
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<li><a href="#llvm_eh_selector"><tt>llvm.eh.selector</tt></a></li>
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<li><a href="#llvm_eh_resume"><tt>llvm.eh.resume</tt></a></li>
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<li><a href="#llvm_eh_typeid_for"><tt>llvm.eh.typeid.for</tt></a></li>
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<li><a href="#llvm_eh_sjlj_setjmp"><tt>llvm.eh.sjlj.setjmp</tt></a></li>
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<li><a href="#llvm_eh_sjlj_longjmp"><tt>llvm.eh.sjlj.longjmp</tt></a></li>
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@ -317,15 +318,28 @@
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<div>
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<p>To handle destructors and cleanups in <tt>try</tt> code, control may not run
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directly from a landing pad to the first catch. Control may actually flow
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from the landing pad to clean up code and then to the first catch. Since the
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required clean up for each <tt>invoke</tt> in a <tt>try</tt> may be different
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(e.g. intervening constructor), there may be several landing pads for a given
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try. If cleanups need to be run, an <tt>i32 0</tt> should be passed as the
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last <a href="#llvm_eh_selector"><tt>llvm.eh.selector</tt></a> argument.
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However, when using DWARF exception handling with C++, a <tt>i8* null</tt>
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<a href="#restrictions">must</a> be passed instead.</p>
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<p>A cleanup is extra code which needs to be run as part of unwinding
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a scope. C++ destructors are a prominent example, but other
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languages and language extensions provide a variety of different
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kinds of cleanup. In general, a landing pad may need to run
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arbitrary amounts of cleanup code before actually entering a catch
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block. To indicate the presence of cleanups, a landing pad's call
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to <a href="#llvm_eh_selector"><tt>llvm.eh.selector</tt></a> should
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end with the argument <tt>i32 0</tt>; otherwise, the unwinder will
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not stop at the landing pad if there are no catches or filters that
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require it to.</p>
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<p>Do not allow a new exception to propagate out of the execution of a
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cleanup. This can corrupt the internal state of the unwinder.
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Different languages describe different high-level semantics for
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these situations: for example, C++ requires that the process be
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terminated, whereas Ada cancels both exceptions and throws a third.</p>
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<p>When all cleanups have completed, if the exception is not handled
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by the current function, resume unwinding by calling the
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<a href="#llvm_eh_resume"><tt>llvm.eh.resume</tt></a> intrinsic,
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passing in the results of <tt>llvm.eh.exception</tt> and
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<tt>llvm.eh.selector</tt> for the original landing pad.</p>
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</div>
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@ -363,22 +377,29 @@
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<div>
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<p>The semantics of the invoke instruction require that any exception that
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unwinds through an invoke call should result in a branch to the invoke's
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unwind label. However such a branch will only happen if the
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<a href="#llvm_eh_selector"><tt>llvm.eh.selector</tt></a> matches. Thus in
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order to ensure correct operation, the front-end must only generate
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<a href="#llvm_eh_selector"><tt>llvm.eh.selector</tt></a> calls that are
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guaranteed to always match whatever exception unwinds through the invoke.
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For most languages it is enough to pass zero, indicating the presence of
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a <a href="#cleanups">cleanup</a>, as the
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last <a href="#llvm_eh_selector"><tt>llvm.eh.selector</tt></a> argument.
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However for C++ this is not sufficient, because the C++ personality function
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will terminate the program if it detects that unwinding the exception only
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results in matches with cleanups. For C++ a <tt>null i8*</tt> should be
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passed as the last <a href="#llvm_eh_selector"><tt>llvm.eh.selector</tt></a>
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argument instead. This is interpreted as a catch-all by the C++ personality
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function, and will always match.</p>
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<p>The unwinder delegates the decision of whether to stop in a call
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frame to that call frame's language-specific personality function.
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Not all personalities functions guarantee that they will stop to
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perform cleanups: for example, the GNU C++ personality doesn't do
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so unless the exception is actually caught somewhere further up the
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stack. When using this personality to implement EH for a language
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that guarantees that cleanups will always be run, be sure to
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indicate a catch-all in the
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<a href="#llvm_eh_selector"><tt>llvm.eh.selector</tt></a> call
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rather than just cleanups.</p>
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<p>In order for inlining to behave correctly, landing pads must be
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prepared to handle selector results that they did not originally
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advertise. Suppose that a function catches exceptions of
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type <tt>A</tt>, and it's inlined into a function that catches
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exceptions of type <tt>B</tt>. The inliner will update the
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selector for the inlined landing pad to include the fact
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that <tt>B</tt> is caught. If that landing pad assumes that it
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will only be entered to catch an <tt>A</tt>, it's in for a rude
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surprise. Consequently, landing pads must test for the selector
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results they understand and then resume exception propagation
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with the <a href="#llvm_eh_resume"><tt>llvm.eh.resume</tt></a>
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intrinsic if none of the conditions match.</p>
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</div>
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@ -424,22 +445,32 @@
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<p>This intrinsic is used to compare the exception with the given type infos,
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filters and cleanups.</p>
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<p><a href="#llvm_eh_selector"><tt>llvm.eh.selector</tt></a> takes a minimum of
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three arguments. The first argument is the reference to the exception
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structure. The second argument is a reference to the personality function to
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be used for this try catch sequence. Each of the remaining arguments is
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either a reference to the type info for a catch statement,
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a <a href="#throw_filters">filter</a> expression, or the number zero
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representing a <a href="#cleanups">cleanup</a>. The exception is tested
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against the arguments sequentially from first to last. The result of
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the <a href="#llvm_eh_selector"><tt>llvm.eh.selector</tt></a> is a positive
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number if the exception matched a type info, a negative number if it matched
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a filter, and zero if it matched a cleanup. If nothing is matched, the
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behaviour of the program is <a href="#restrictions">undefined</a>. If a type
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info matched then the selector value is the index of the type info in the
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exception table, which can be obtained using the
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<p><a href="#llvm_eh_selector"><tt>llvm.eh.selector</tt></a> takes a
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minimum of three arguments. The first argument is the reference to
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the exception structure. The second argument is a reference to the
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personality function to be used for this try catch sequence. Each
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of the remaining arguments is either a reference to the type info
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for a catch statement, a <a href="#throw_filters">filter</a>
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expression, or the number zero representing
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a <a href="#cleanups">cleanup</a>. The exception is tested against
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the arguments sequentially from first to last. The result of
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the <a href="#llvm_eh_selector"><tt>llvm.eh.selector</tt></a> is a
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positive number if the exception matched a type info, a negative
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number if it matched a filter, and zero if it matched a cleanup.
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If nothing is matched, or if only a cleanup is matched, different
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personality functions may or may not cause control to stop at the
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landing pad; see <a href="#restrictions">the restrictions</a> for
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more information. If a type info matched then the selector value
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is the index of the type info in the exception table, which can be
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obtained using the
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<a href="#llvm_eh_typeid_for"><tt>llvm.eh.typeid.for</tt></a> intrinsic.</p>
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<p>If a landing pad containing a call to <tt>llvm.eh.selector</tt> is
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inlined into an <tt>invoke</tt> instruction, the selector arguments
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for the outer landing pad are appended to those of the inlined
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landing pad. Consequently, landing pads must be written to ignore
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selector values that they did not originally advertise.</p>
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</div>
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<!-- ======================================================================= -->
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@ -460,6 +491,33 @@
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</div>
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<!-- ======================================================================= -->
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<h4>
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<a name="llvm_eh_resume">llvm.eh.resume</a>
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</h4>
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<div>
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<pre>
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void %<a href="#llvm_eh_resume">llvm.eh.resume</a>(i8*, i32) noreturn
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</pre>
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<p>This intrinsic is used to resume propagation of an exception after
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landing at a landing pad. The first argument should be the result
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of <a href="#llvm_eh_exception">llvm.eh.exception</a> for that
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landing pad, and the second argument should be the result of
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<a href="#llvm_eh_selector">llvm.eh.selector</a>. When a call to
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this intrinsic is inlined into an invoke, the call is transformed
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into a branch to the invoke's unwind destination, using its
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arguments in place of the calls
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to <a href="#llvm_eh_exception">llvm.eh.exception</a> and
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<a href="#llvm_eh_selector">llvm.eh.selector</a> there.</p>
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<p>This intrinsic is not implicitly <tt>nounwind</tt>; calls to it
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will always throw. It may not be invoked.</p>
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</div>
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<!-- ======================================================================= -->
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<h4>
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<a name="llvm_eh_sjlj_setjmp">llvm.eh.sjlj.setjmp</a>
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@ -30,6 +30,7 @@ using namespace llvm;
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STATISTIC(NumLandingPadsSplit, "Number of landing pads split");
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STATISTIC(NumUnwindsLowered, "Number of unwind instructions lowered");
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STATISTIC(NumResumesLowered, "Number of eh.resume calls lowered");
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STATISTIC(NumExceptionValuesMoved, "Number of eh.exception calls moved");
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namespace {
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@ -63,7 +64,7 @@ namespace {
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BBSet LandingPads;
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bool NormalizeLandingPads();
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bool LowerUnwinds();
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bool LowerUnwindsAndResumes();
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bool MoveExceptionValueCalls();
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Instruction *CreateExceptionValueCall(BasicBlock *BB);
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@ -480,20 +481,25 @@ bool DwarfEHPrepare::NormalizeLandingPads() {
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/// rethrowing any previously caught exception. This will crash horribly
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/// at runtime if there is no such exception: using unwind to throw a new
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/// exception is currently not supported.
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bool DwarfEHPrepare::LowerUnwinds() {
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SmallVector<TerminatorInst*, 16> UnwindInsts;
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bool DwarfEHPrepare::LowerUnwindsAndResumes() {
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SmallVector<Instruction*, 16> ResumeInsts;
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for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
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TerminatorInst *TI = I->getTerminator();
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if (isa<UnwindInst>(TI))
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UnwindInsts.push_back(TI);
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for (Function::iterator fi = F->begin(), fe = F->end(); fi != fe; ++fi) {
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for (BasicBlock::iterator bi = fi->begin(), be = fi->end(); bi != be; ++bi){
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if (isa<UnwindInst>(bi))
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ResumeInsts.push_back(bi);
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else if (CallInst *call = dyn_cast<CallInst>(bi))
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if (Function *fn = dyn_cast<Function>(call->getCalledValue()))
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if (fn->getName() == "llvm.eh.resume")
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ResumeInsts.push_back(bi);
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}
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}
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if (UnwindInsts.empty()) return false;
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if (ResumeInsts.empty()) return false;
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// Find the rewind function if we didn't already.
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if (!RewindFunction) {
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LLVMContext &Ctx = UnwindInsts[0]->getContext();
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LLVMContext &Ctx = ResumeInsts[0]->getContext();
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std::vector<const Type*>
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Params(1, Type::getInt8PtrTy(Ctx));
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FunctionType *FTy = FunctionType::get(Type::getVoidTy(Ctx),
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@ -504,24 +510,35 @@ bool DwarfEHPrepare::LowerUnwinds() {
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bool Changed = false;
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for (SmallVectorImpl<TerminatorInst*>::iterator
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I = UnwindInsts.begin(), E = UnwindInsts.end(); I != E; ++I) {
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TerminatorInst *TI = *I;
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for (SmallVectorImpl<Instruction*>::iterator
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I = ResumeInsts.begin(), E = ResumeInsts.end(); I != E; ++I) {
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Instruction *RI = *I;
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// Replace the unwind instruction with a call to _Unwind_Resume (or the
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// appropriate target equivalent) followed by an UnreachableInst.
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// Replace the resuming instruction with a call to _Unwind_Resume (or the
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// appropriate target equivalent).
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llvm::Value *ExnValue;
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if (isa<UnwindInst>(RI))
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ExnValue = CreateExceptionValueCall(RI->getParent());
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else
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ExnValue = cast<CallInst>(RI)->getArgOperand(0);
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// Create the call...
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CallInst *CI = CallInst::Create(RewindFunction,
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CreateExceptionValueCall(TI->getParent()),
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"", TI);
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CallInst *CI = CallInst::Create(RewindFunction, ExnValue, "", RI);
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CI->setCallingConv(TLI->getLibcallCallingConv(RTLIB::UNWIND_RESUME));
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// ...followed by an UnreachableInst.
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new UnreachableInst(TI->getContext(), TI);
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// Nuke the unwind instruction.
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TI->eraseFromParent();
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++NumUnwindsLowered;
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// ...followed by an UnreachableInst, if it was an unwind.
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// Calls to llvm.eh.resume are typically already followed by this.
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if (isa<UnwindInst>(RI))
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new UnreachableInst(RI->getContext(), RI);
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// Nuke the resume instruction.
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RI->eraseFromParent();
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if (isa<UnwindInst>(RI))
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++NumUnwindsLowered;
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else
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++NumResumesLowered;
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Changed = true;
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}
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@ -657,8 +674,8 @@ bool DwarfEHPrepare::runOnFunction(Function &Fn) {
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// basic block where an invoke unwind edge ends).
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Changed |= NormalizeLandingPads();
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// Turn unwind instructions into libcalls.
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Changed |= LowerUnwinds();
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// Turn unwind instructions and eh.resume calls into libcalls.
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Changed |= LowerUnwindsAndResumes();
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// TODO: Move eh.selector calls to landing pads and combine them.
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@ -45,66 +45,192 @@ bool llvm::InlineFunction(InvokeInst *II, InlineFunctionInfo &IFI) {
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return InlineFunction(CallSite(II), IFI);
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}
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/// [LIBUNWIND] Find the (possibly absent) call to @llvm.eh.selector in
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/// the given landing pad.
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static EHSelectorInst *findSelectorForLandingPad(BasicBlock *lpad) {
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// The llvm.eh.exception call is required to be in the landing pad.
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for (BasicBlock::iterator i = lpad->begin(), e = lpad->end(); i != e; i++) {
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EHExceptionInst *exn = dyn_cast<EHExceptionInst>(i);
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if (!exn) continue;
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EHSelectorInst *selector = 0;
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for (Instruction::use_iterator
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ui = exn->use_begin(), ue = exn->use_end(); ui != ue; ++ui) {
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EHSelectorInst *sel = dyn_cast<EHSelectorInst>(*ui);
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if (!sel) continue;
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// Immediately accept an eh.selector in the landing pad.
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if (sel->getParent() == lpad) return sel;
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// Otherwise, use the first selector we see.
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if (!selector) selector = sel;
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}
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return selector;
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}
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return 0;
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}
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namespace {
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/// A class for recording information about inlining through an invoke.
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class InvokeInliningInfo {
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BasicBlock *UnwindDest;
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BasicBlock *OuterUnwindDest;
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EHSelectorInst *OuterSelector;
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BasicBlock *InnerUnwindDest;
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PHINode *InnerExceptionPHI;
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PHINode *InnerSelectorPHI;
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SmallVector<Value*, 8> UnwindDestPHIValues;
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public:
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InvokeInliningInfo(InvokeInst *II) : UnwindDest(II->getUnwindDest()) {
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InvokeInliningInfo(InvokeInst *II) :
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OuterUnwindDest(II->getUnwindDest()), OuterSelector(0),
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InnerUnwindDest(0), InnerExceptionPHI(0), InnerSelectorPHI(0) {
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// If there are PHI nodes in the unwind destination block, we
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// need to keep track of which values came into them from the
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// invoke before removing the edge from this block.
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llvm::BasicBlock *InvokeBlock = II->getParent();
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for (BasicBlock::iterator I = UnwindDest->begin(); isa<PHINode>(I); ++I) {
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PHINode *PN = cast<PHINode>(I);
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llvm::BasicBlock *invokeBB = II->getParent();
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for (BasicBlock::iterator I = OuterUnwindDest->begin();
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isa<PHINode>(I); ++I) {
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// Save the value to use for this edge.
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llvm::Value *Incoming = PN->getIncomingValueForBlock(InvokeBlock);
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UnwindDestPHIValues.push_back(Incoming);
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PHINode *phi = cast<PHINode>(I);
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UnwindDestPHIValues.push_back(phi->getIncomingValueForBlock(invokeBB));
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}
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}
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BasicBlock *getUnwindDest() const {
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return UnwindDest;
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/// The outer unwind destination is the target of unwind edges
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/// introduced for calls within the inlined function.
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BasicBlock *getOuterUnwindDest() const {
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return OuterUnwindDest;
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}
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EHSelectorInst *getOuterSelector() {
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if (!OuterSelector)
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OuterSelector = findSelectorForLandingPad(OuterUnwindDest);
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return OuterSelector;
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}
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BasicBlock *getInnerUnwindDest();
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bool forwardEHResume(CallInst *call, BasicBlock *src);
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/// Add incoming-PHI values to the unwind destination block for
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/// the given basic block, using the values for the original
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/// invoke's source block.
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void addIncomingPHIValuesFor(BasicBlock *BB) const {
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BasicBlock::iterator I = UnwindDest->begin();
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addIncomingPHIValuesForInto(BB, OuterUnwindDest);
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}
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void addIncomingPHIValuesForInto(BasicBlock *src, BasicBlock *dest) const {
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BasicBlock::iterator I = dest->begin();
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for (unsigned i = 0, e = UnwindDestPHIValues.size(); i != e; ++i, ++I) {
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PHINode *PN = cast<PHINode>(I);
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PN->addIncoming(UnwindDestPHIValues[i], BB);
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PHINode *phi = cast<PHINode>(I);
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phi->addIncoming(UnwindDestPHIValues[i], src);
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}
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}
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};
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}
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/// [LIBUNWIND] Check whether the given value is the _Unwind_Resume
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/// function specified by the Itanium EH ABI.
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static bool isUnwindResume(Value *value) {
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Function *fn = dyn_cast<Function>(value);
|
||||
if (!fn) return false;
|
||||
|
||||
// declare void @_Unwind_Resume(i8*)
|
||||
if (fn->getName() != "_Unwind_Resume") return false;
|
||||
const FunctionType *fnType = fn->getFunctionType();
|
||||
if (!fnType->getReturnType()->isVoidTy()) return false;
|
||||
if (fnType->isVarArg()) return false;
|
||||
if (fnType->getNumParams() != 1) return false;
|
||||
const PointerType *paramType = dyn_cast<PointerType>(fnType->getParamType(0));
|
||||
return (paramType && paramType->getElementType()->isIntegerTy(8));
|
||||
/// Replace all the instruction uses of a value with a different value.
|
||||
/// This has the advantage of not screwing up the CallGraph.
|
||||
static void replaceAllInsnUsesWith(Instruction *insn, Value *replacement) {
|
||||
for (Value::use_iterator i = insn->use_begin(), e = insn->use_end();
|
||||
i != e; ) {
|
||||
Use &use = i.getUse();
|
||||
++i;
|
||||
if (isa<Instruction>(use.getUser()))
|
||||
use.set(replacement);
|
||||
}
|
||||
}
|
||||
|
||||
/// [LIBUNWIND] Find the (possibly absent) call to @llvm.eh.selector in
|
||||
/// the given landing pad.
|
||||
static EHSelectorInst *findSelectorForLandingPad(BasicBlock *lpad) {
|
||||
for (BasicBlock::iterator i = lpad->begin(), e = lpad->end(); i != e; i++)
|
||||
if (EHSelectorInst *selector = dyn_cast<EHSelectorInst>(i))
|
||||
return selector;
|
||||
return 0;
|
||||
/// Get or create a target for the branch out of rewritten calls to
|
||||
/// llvm.eh.resume.
|
||||
BasicBlock *InvokeInliningInfo::getInnerUnwindDest() {
|
||||
if (InnerUnwindDest) return InnerUnwindDest;
|
||||
|
||||
// Find and hoist the llvm.eh.exception and llvm.eh.selector calls
|
||||
// in the outer landing pad to immediately following the phis.
|
||||
EHSelectorInst *selector = getOuterSelector();
|
||||
if (!selector) return 0;
|
||||
|
||||
// The call to llvm.eh.exception *must* be in the landing pad.
|
||||
Instruction *exn = cast<Instruction>(selector->getArgOperand(0));
|
||||
assert(exn->getParent() == OuterUnwindDest);
|
||||
|
||||
// TODO: recognize when we've already done this, so that we don't
|
||||
// get a linear number of these when inlining calls into lots of
|
||||
// invokes with the same landing pad.
|
||||
|
||||
// Do the hoisting.
|
||||
Instruction *splitPoint = exn->getParent()->getFirstNonPHI();
|
||||
assert(splitPoint != selector && "selector-on-exception dominance broken!");
|
||||
if (splitPoint == exn) {
|
||||
selector->removeFromParent();
|
||||
selector->insertAfter(exn);
|
||||
splitPoint = selector->getNextNode();
|
||||
} else {
|
||||
exn->moveBefore(splitPoint);
|
||||
selector->moveBefore(splitPoint);
|
||||
}
|
||||
|
||||
// Split the landing pad.
|
||||
InnerUnwindDest = OuterUnwindDest->splitBasicBlock(splitPoint,
|
||||
OuterUnwindDest->getName() + ".body");
|
||||
|
||||
// The number of incoming edges we expect to the inner landing pad.
|
||||
const unsigned phiCapacity = 2;
|
||||
|
||||
// Create corresponding new phis for all the phis in the outer landing pad.
|
||||
BasicBlock::iterator insertPoint = InnerUnwindDest->begin();
|
||||
BasicBlock::iterator I = OuterUnwindDest->begin();
|
||||
for (unsigned i = 0, e = UnwindDestPHIValues.size(); i != e; ++i, ++I) {
|
||||
PHINode *outerPhi = cast<PHINode>(I);
|
||||
PHINode *innerPhi = PHINode::Create(outerPhi->getType(), phiCapacity,
|
||||
outerPhi->getName() + ".lpad-body",
|
||||
insertPoint);
|
||||
innerPhi->addIncoming(outerPhi, OuterUnwindDest);
|
||||
}
|
||||
|
||||
// Create a phi for the exception value...
|
||||
InnerExceptionPHI = PHINode::Create(exn->getType(), phiCapacity,
|
||||
"exn.lpad-body", insertPoint);
|
||||
replaceAllInsnUsesWith(exn, InnerExceptionPHI);
|
||||
selector->setArgOperand(0, exn); // restore this use
|
||||
InnerExceptionPHI->addIncoming(exn, OuterUnwindDest);
|
||||
|
||||
// ...and the selector.
|
||||
InnerSelectorPHI = PHINode::Create(selector->getType(), phiCapacity,
|
||||
"selector.lpad-body", insertPoint);
|
||||
replaceAllInsnUsesWith(selector, InnerSelectorPHI);
|
||||
InnerSelectorPHI->addIncoming(selector, OuterUnwindDest);
|
||||
|
||||
// All done.
|
||||
return InnerUnwindDest;
|
||||
}
|
||||
|
||||
/// [LIBUNWIND] Try to forward the given call, which logically occurs
|
||||
/// at the end of the given block, as a branch to the inner unwind
|
||||
/// block. Returns true if the call was forwarded.
|
||||
bool InvokeInliningInfo::forwardEHResume(CallInst *call, BasicBlock *src) {
|
||||
Function *fn = dyn_cast<Function>(call->getCalledValue());
|
||||
if (!fn || fn->getName() != "llvm.eh.resume")
|
||||
return false;
|
||||
|
||||
// If this fails, maybe it should be a fatal error.
|
||||
BasicBlock *dest = getInnerUnwindDest();
|
||||
if (!dest) return false;
|
||||
|
||||
// Make a branch.
|
||||
BranchInst::Create(dest, src);
|
||||
|
||||
// Update the phis in the destination. They were inserted in an
|
||||
// order which makes this work.
|
||||
addIncomingPHIValuesForInto(src, dest);
|
||||
InnerExceptionPHI->addIncoming(call->getArgOperand(0), src);
|
||||
InnerSelectorPHI->addIncoming(call->getArgOperand(1), src);
|
||||
|
||||
return true;
|
||||
}
|
||||
|
||||
/// [LIBUNWIND] Check whether this selector is "only cleanups":
|
||||
@ -134,7 +260,7 @@ static bool HandleCallsInBlockInlinedThroughInvoke(BasicBlock *BB,
|
||||
|
||||
// LIBUNWIND: merge selector instructions.
|
||||
if (EHSelectorInst *Inner = dyn_cast<EHSelectorInst>(CI)) {
|
||||
EHSelectorInst *Outer = findSelectorForLandingPad(Invoke.getUnwindDest());
|
||||
EHSelectorInst *Outer = Invoke.getOuterSelector();
|
||||
if (!Outer) continue;
|
||||
|
||||
bool innerIsOnlyCleanup = isCleanupOnlySelector(Inner);
|
||||
@ -172,48 +298,41 @@ static bool HandleCallsInBlockInlinedThroughInvoke(BasicBlock *BB,
|
||||
// First, split the basic block.
|
||||
BasicBlock *Split = BB->splitBasicBlock(CI, CI->getName()+".noexc");
|
||||
|
||||
bool skipNextBlock = false;
|
||||
// Delete the unconditional branch inserted by splitBasicBlock
|
||||
BB->getInstList().pop_back();
|
||||
|
||||
// LIBUNWIND: If this is a call to @_Unwind_Resume, just branch
|
||||
// LIBUNWIND: If this is a call to @llvm.eh.resume, just branch
|
||||
// directly to the new landing pad.
|
||||
if (isUnwindResume(CI->getCalledValue())) {
|
||||
BranchInst::Create(Invoke.getUnwindDest(), BB->getTerminator());
|
||||
|
||||
if (Invoke.forwardEHResume(CI, BB)) {
|
||||
// TODO: 'Split' is now unreachable; clean it up.
|
||||
|
||||
// We want to leave the original call intact so that the call
|
||||
// graph and other structures won't get misled. We also have to
|
||||
// avoid processing the next block, or we'll iterate here forever.
|
||||
skipNextBlock = true;
|
||||
return true;
|
||||
}
|
||||
|
||||
// Otherwise, create the new invoke instruction.
|
||||
} else {
|
||||
ImmutableCallSite CS(CI);
|
||||
SmallVector<Value*, 8> InvokeArgs(CS.arg_begin(), CS.arg_end());
|
||||
InvokeInst *II =
|
||||
InvokeInst::Create(CI->getCalledValue(), Split, Invoke.getUnwindDest(),
|
||||
InvokeArgs.begin(), InvokeArgs.end(),
|
||||
CI->getName(), BB->getTerminator());
|
||||
II->setCallingConv(CI->getCallingConv());
|
||||
II->setAttributes(CI->getAttributes());
|
||||
ImmutableCallSite CS(CI);
|
||||
SmallVector<Value*, 8> InvokeArgs(CS.arg_begin(), CS.arg_end());
|
||||
InvokeInst *II =
|
||||
InvokeInst::Create(CI->getCalledValue(), Split,
|
||||
Invoke.getOuterUnwindDest(),
|
||||
InvokeArgs.begin(), InvokeArgs.end(),
|
||||
CI->getName(), BB);
|
||||
II->setCallingConv(CI->getCallingConv());
|
||||
II->setAttributes(CI->getAttributes());
|
||||
|
||||
// Make sure that anything using the call now uses the invoke! This also
|
||||
// updates the CallGraph if present, because it uses a WeakVH.
|
||||
CI->replaceAllUsesWith(II);
|
||||
// Make sure that anything using the call now uses the invoke! This also
|
||||
// updates the CallGraph if present, because it uses a WeakVH.
|
||||
CI->replaceAllUsesWith(II);
|
||||
|
||||
Split->getInstList().pop_front(); // Delete the original call
|
||||
|
||||
Split->getInstList().pop_front(); // Delete the original call
|
||||
}
|
||||
|
||||
// Delete the unconditional branch inserted by splitBasicBlock
|
||||
BB->getInstList().pop_back();
|
||||
|
||||
// Update any PHI nodes in the exceptional block to indicate that
|
||||
// there is now a new entry in them.
|
||||
Invoke.addIncomingPHIValuesFor(BB);
|
||||
|
||||
// This basic block is now complete, the caller will continue scanning the
|
||||
// next one.
|
||||
return skipNextBlock;
|
||||
return false;
|
||||
}
|
||||
|
||||
return false;
|
||||
|
||||
@ -18,7 +18,7 @@ declare i32 @llvm.eh.selector(i8*, i8*, ...) nounwind
|
||||
|
||||
declare i32 @llvm.eh.typeid.for(i8*) nounwind
|
||||
|
||||
declare void @_Unwind_Resume(i8*)
|
||||
declare void @llvm.eh.resume(i8*, i32)
|
||||
|
||||
declare i32 @__gxx_personality_v0(...)
|
||||
|
||||
@ -51,7 +51,7 @@ lpad:
|
||||
to label %invoke.cont2 unwind label %terminate.lpad
|
||||
|
||||
invoke.cont2:
|
||||
call void @_Unwind_Resume(i8* %exn) noreturn
|
||||
call void @llvm.eh.resume(i8* %exn, i32 %eh.selector) noreturn
|
||||
unreachable
|
||||
|
||||
terminate.lpad:
|
||||
@ -82,22 +82,27 @@ catch:
|
||||
br label %ret
|
||||
|
||||
eh.resume:
|
||||
call void @_Unwind_Resume(i8* %exn) noreturn
|
||||
call void @llvm.eh.resume(i8* %exn, i32 %eh.selector) noreturn
|
||||
unreachable
|
||||
}
|
||||
|
||||
; CHECK: define void @test0_out()
|
||||
; CHECK: [[A:%.*]] = alloca %struct.A,
|
||||
; CHECK: [[B:%.*]] = alloca %struct.A,
|
||||
; CHECK: invoke void @_ZN1AC1Ev(%struct.A* [[A]])
|
||||
; CHECK: invoke void @_ZN1AC1Ev(%struct.A* [[B]])
|
||||
; CHECK: invoke void @_ZN1AD1Ev(%struct.A* [[B]])
|
||||
; CHECK: invoke void @_ZN1AD1Ev(%struct.A* [[A]])
|
||||
; CHECK: call i32 (i8*, i8*, ...)* @llvm.eh.selector(i8* {{%.*}}, i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*), i32 0, i8* bitcast (i8** @_ZTIi to i8*))
|
||||
; CHECK: define void @test0_out()
|
||||
; CHECK: [[A:%.*]] = alloca %struct.A,
|
||||
; CHECK: [[B:%.*]] = alloca %struct.A,
|
||||
; CHECK: invoke void @_ZN1AC1Ev(%struct.A* [[A]])
|
||||
; CHECK: invoke void @_ZN1AC1Ev(%struct.A* [[B]])
|
||||
; CHECK: invoke void @_ZN1AD1Ev(%struct.A* [[B]])
|
||||
; CHECK: invoke void @_ZN1AD1Ev(%struct.A* [[A]])
|
||||
; CHECK: call i32 (i8*, i8*, ...)* @llvm.eh.selector(i8* {{%.*}}, i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*), i32 0, i8* bitcast (i8** @_ZTIi to i8*))
|
||||
; CHECK-NEXT: invoke void @_ZN1AD1Ev(%struct.A* [[A]])
|
||||
; CHECK-NEXT: to label %[[LBL:[^\s]+]] unwind
|
||||
; CHECK: [[LBL]]:
|
||||
; CHECK-NEXT: br label %[[LPAD:[^\s]+]]
|
||||
; CHECK: [[LPAD]]:
|
||||
; CHECK-NEXT: call i8* @llvm.eh.exception()
|
||||
; CHECK: ret void
|
||||
; CHECK: call i8* @llvm.eh.exception()
|
||||
; CHECK-NEXT: call i32 (i8*, i8*, ...)* @llvm.eh.selector(i8* {{%.*}}, i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*), i8* bitcast (i8** @_ZTIi to i8*))
|
||||
; CHECK-NEXT: br label %[[LPAD]]
|
||||
; CHECK: [[LPAD]]:
|
||||
; CHECK-NEXT: phi i8* [
|
||||
; CHECK-NEXT: phi i32 [
|
||||
; CHECK-NEXT: call i32 @llvm.eh.typeid.for(
|
||||
Loading…
Reference in New Issue
Block a user