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[LoopUnroll] Unroll loops which have exit blocks to EH pads

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We were overly cautious in our analysis of loops which have invokes
which unwind to EH pads.  The loop unroll transform is safe because it
only clones blocks in the loop body, it does not try to split critical
edges involving EH pads.  Instead, move the necessary safety check to
LoopUnswitch.

N.B. The safety check for loop unswitch is covered by an existing test
which fails without it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@268357 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
David Majnemer 2016-05-03 03:57:40 +00:00
parent a802e2acad
commit 67d4f302ed
4 changed files with 56 additions and 16 deletions
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8
include/llvm/IR/CallSite.h
View File

@ -426,6 +426,14 @@ public:
CALLSITE_DELEGATE_SETTER(setDoesNotThrow());
}
/// @brief Determine if the call can be duplicated.
bool cannotDuplicate() const {
CALLSITE_DELEGATE_GETTER(cannotDuplicate());
}
void setCannotDuplicate() {
CALLSITE_DELEGATE_GETTER(setCannotDuplicate());
}
/// @brief Determine if the call is convergent.
bool isConvergent() const {
CALLSITE_DELEGATE_GETTER(isConvergent());

19
lib/Analysis/LoopInfo.cpp
View File

@ -195,23 +195,10 @@ bool Loop::isSafeToClone() const {
if (isa<IndirectBrInst>(BB->getTerminator()))
return false;
if (const InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
if (II->cannotDuplicate())
return false;
// Return false if any loop blocks contain invokes to EH-pads other than
// landingpads; we don't know how to split those edges yet.
auto *FirstNonPHI = II->getUnwindDest()->getFirstNonPHI();
if (FirstNonPHI->isEHPad() && !isa<LandingPadInst>(FirstNonPHI))
return false;
}
for (Instruction &I : *BB) {
if (const CallInst *CI = dyn_cast<CallInst>(&I)) {
if (CI->cannotDuplicate())
for (Instruction &I : *BB)
if (auto CS = CallSite(&I))
if (CS.cannotDuplicate())
return false;
}
if (I.getType()->isTokenTy() && I.isUsedOutsideOfBlock(BB))
return false;
}
}
return true;
}

5
lib/Transforms/Scalar/LoopUnswitch.cpp
View File

@ -500,6 +500,11 @@ bool LoopUnswitch::processCurrentLoop() {
if (!CS) continue;
if (CS.hasFnAttr(Attribute::Convergent))
return false;
// Return false if any loop blocks contain invokes whose predecessor edges
// we cannot split.
if (auto *II = dyn_cast<InvokeInst>(&I))
if (!II->getUnwindDest()->canSplitPredecessors())
return false;
}
}

40
test/Transforms/LoopUnroll/unroll-cleanuppad.ll Normal file
View File

@ -0,0 +1,40 @@
; RUN: opt -S -loop-unroll %s | FileCheck %s
target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-pc-windows-msvc18.0.0"
define void @test1() personality i32 (...)* @__CxxFrameHandler3 {
entry:
br label %for.body
for.body: ; preds = %entry, %for.inc
%phi = phi i32 [ 0, %entry ], [ %inc, %for.inc ]
invoke void @callee(i32 %phi)
to label %for.inc unwind label %ehcleanup
for.inc: ; preds = %for.body
%inc = add nuw nsw i32 %phi, 1
%cmp = icmp slt i32 %inc, 3
br i1 %cmp, label %for.body, label %for.cond.cleanup
for.cond.cleanup: ; preds = %for.inc
call void @dtor()
ret void
ehcleanup: ; preds = %for.body
%cp = cleanuppad within none []
call void @dtor() [ "funclet"(token %cp) ]
cleanupret from %cp unwind to caller
}
; CHECK-LABEL: define void @test1(
; CHECK: invoke void @callee(i32 0
; CHECK: invoke void @callee(i32 1
; CHECK: invoke void @callee(i32 2
declare void @callee(i32)
declare i32 @__CxxFrameHandler3(...)
declare void @dtor()