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Don't insert lifetime.end markers between a musttail call and ret

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The allocas going out of scope are immediately killed by the return
instruction.

Reviewers: chandlerc

Differential Revision: http://reviews.llvm.org/D3630

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208912 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Reid Kleckner 2014-05-15 20:39:13 +00:00
parent 44623e8781
commit 24a50c5797
2 changed files with 48 additions and 2 deletions
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14
lib/Transforms/Utils/InlineFunction.cpp
View File

@ -758,8 +758,13 @@ bool llvm::InlineFunction(CallSite CS, InlineFunctionInfo &IFI,
}
builder.CreateLifetimeStart(AI, AllocaSize);
for (ReturnInst *RI : Returns)
for (ReturnInst *RI : Returns) {
// Don't insert llvm.lifetime.end calls between a musttail call and a
// return. The return kills all local allocas.
if (InlinedMustTailCalls && getPrecedingMustTailCall(RI))
continue;
IRBuilder<>(RI).CreateLifetimeEnd(AI, AllocaSize);
}
}
}
@ -777,8 +782,13 @@ bool llvm::InlineFunction(CallSite CS, InlineFunctionInfo &IFI,
// Insert a call to llvm.stackrestore before any return instructions in the
// inlined function.
for (ReturnInst *RI : Returns)
for (ReturnInst *RI : Returns) {
// Don't insert llvm.stackrestore calls between a musttail call and a
// return. The return will restore the stack pointer.
if (InlinedMustTailCalls && getPrecedingMustTailCall(RI))
continue;
IRBuilder<>(RI).CreateCall(StackRestore, SavedPtr);
}
}
// If we are inlining for an invoke instruction, we must make sure to rewrite

36
test/Transforms/Inline/inline-tail.ll
View File

@ -49,6 +49,42 @@ define void @test_musttail_basic_a(i32* %p) {
ret void
}
; Don't insert lifetime end markers here, the lifetime is trivially over due
; the return.
; CHECK: define void @test_byval_a(
; CHECK: musttail call void @test_byval_c(
; CHECK-NEXT: ret void
declare void @test_byval_c(i32* byval %p)
define internal void @test_byval_b(i32* byval %p) {
musttail call void @test_byval_c(i32* byval %p)
ret void
}
define void @test_byval_a(i32* byval %p) {
musttail call void @test_byval_b(i32* byval %p)
ret void
}
; Don't insert a stack restore, we're about to return.
; CHECK: define void @test_dynalloca_a(
; CHECK: call i8* @llvm.stacksave(
; CHECK: alloca i8, i32 %n
; CHECK: musttail call void @test_dynalloca_c(
; CHECK-NEXT: ret void
declare void @escape(i8* %buf)
declare void @test_dynalloca_c(i32* byval %p, i32 %n)
define internal void @test_dynalloca_b(i32* byval %p, i32 %n) alwaysinline {
%buf = alloca i8, i32 %n ; dynamic alloca
call void @escape(i8* %buf) ; escape it
musttail call void @test_dynalloca_c(i32* byval %p, i32 %n)
ret void
}
define void @test_dynalloca_a(i32* byval %p, i32 %n) {
musttail call void @test_dynalloca_b(i32* byval %p, i32 %n)
ret void
}
; We can't merge the returns.
; CHECK: define void @test_multiret_a(
; CHECK: musttail call void @test_multiret_c(