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Don't assume a tail call can't reference a byval 

argument to the outer function, this isn't correct.

llvm-svn: 49731
This commit is contained in:
Dale Johannesen 2008-04-15 17:41:34 +00:00
parent 53d3241b52
commit 8fc8a272e0
2 changed files with 22 additions and 2 deletions
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6
llvm/lib/Analysis/BasicAliasAnalysis.cpp
View File

@ -273,8 +273,10 @@ BasicAliasAnalysis::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
// If this is a tail call and P points to a stack location, we know that
// the tail call cannot access or modify the local stack.
if (isa<AllocaInst>(Object) ||
(isa<Argument>(Object) && cast<Argument>(Object)->hasByValAttr()))
// We cannot exclude byval arguments here; these belong to the caller of
// the current function not to the current function, and a tail callee
// may reference them.
if (isa<AllocaInst>(Object))
if (CallInst *CI = dyn_cast<CallInst>(CS.getInstruction()))
if (CI->isTailCall())
return NoModRef;

18
llvm/test/Analysis/BasicAA/2008-04-15-Byval.ll Normal file
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@ -0,0 +1,18 @@
; RUN: llvm-as < %s | opt -std-compile-opts | llvm-dis | grep store
; ModuleID = 'small2.c'
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
target triple = "i386-apple-darwin8"
%struct.x = type { [4 x i32] }
define void @foo(%struct.x* byval align 4 %X) nounwind {
entry:
%tmp = getelementptr %struct.x* %X, i32 0, i32 0 ; <[4 x i32]*> [#uses=1]
%tmp1 = getelementptr [4 x i32]* %tmp, i32 0, i32 3 ; <i32*> [#uses=1]
store i32 2, i32* %tmp1, align 4
%tmp2 = call i32 (...)* @bar( %struct.x* byval align 4 %X ) nounwind ; <i32> [#uses=0]
br label %return
return: ; preds = %entry
ret void
}
declare i32 @bar(...)