#include "llvm/DerivedTypes.h"
#include "llvm/Instructions.h"
#include "llvm/Intrinsics.h"
+#include "llvm/IntrinsicInst.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
bool llvm::isInstructionTriviallyDead(Instruction *I) {
if (!I->use_empty() || isa<TerminatorInst>(I)) return false;
- if (!I->mayWriteToMemory()) return true;
+ if (!I->mayWriteToMemory())
+ return true;
+ // Special case intrinsics that "may write to memory" but can be deleted when
+ // dead.
+ if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I))
+ // Safe to delete llvm.stacksave if dead.
+ if (II->getIntrinsicID() == Intrinsic::stacksave)
+ return true;
+
return false;
}
; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {ret i32 %A}
+; RUN: llvm-as < %s | opt -die | llvm-dis | not grep call.*llvm.stacksave
define i32 @test(i32 %A) {
%X = or i1 false, false
%C.upgrd.1 = phi i32 [ %B, %T ], [ %A, %0 ]
ret i32 %C.upgrd.1
}
+
+define i32* @test2(i32 %width) {
+ %tmp = call i8* @llvm.stacksave( )
+ %tmp14 = alloca i32, i32 %width
+ ret i32* %tmp14
+}
+
+declare i8* @llvm.stacksave()
+