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Don't promote volatile loads/stores. This is needed (for example) to handle setjmp/longjmp properly.

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This fixes PR1520.

llvm-svn: 41461
This commit is contained in:
Anton Korobeynikov 2007-08-26 21:43:30 +00:00
parent f660f11ec4
commit 3dffac0c59
2 changed files with 53 additions and 3 deletions
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9
lib/Transforms/Utils/PromoteMemoryToRegister.cpp
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@ -63,14 +63,17 @@ bool llvm::isAllocaPromotable(const AllocaInst *AI) {
// FIXME: If the memory unit is of pointer or integer type, we can permit
// assignments to subsections of the memory unit.
// Only allow direct loads and stores...
// Only allow direct and non-volatile loads and stores...
for (Value::use_const_iterator UI = AI->use_begin(), UE = AI->use_end();
UI != UE; ++UI) // Loop over all of the uses of the alloca
if (isa<LoadInst>(*UI)) {
// noop
if (const LoadInst *LI = dyn_cast<LoadInst>(*UI)) {
if (LI->isVolatile())
return false;
} else if (const StoreInst *SI = dyn_cast<StoreInst>(*UI)) {
if (SI->getOperand(0) == AI)
return false; // Don't allow a store OF the AI, only INTO the AI.
if (SI->isVolatile())
return false;
} else {
return false; // Not a load or store.
}

47
test/Transforms/Mem2Reg/2007-08-27-VolatileLoadsStores.ll Normal file
View File

@ -0,0 +1,47 @@
; RUN: llvm-as < %s | opt -std-compile-opts | llvm-dis | grep volatile | count 3
; PR1520
; Don't promote volatile loads/stores. This is really needed to handle setjmp/lonjmp properly.
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-f80:32:32"
target triple = "i686-pc-linux-gnu"
%struct.__jmp_buf_tag = type { [6 x i32], i32, %struct.__sigset_t }
%struct.__sigset_t = type { [32 x i32] }
@j = external global [1 x %struct.__jmp_buf_tag] ; <[1 x %struct.__jmp_buf_tag]*> [#uses=1]
define i32 @f() {
entry:
%retval = alloca i32, align 4 ; <i32*> [#uses=2]
%v = alloca i32, align 4 ; <i32*> [#uses=3]
%tmp = alloca i32, align 4 ; <i32*> [#uses=3]
%"alloca point" = bitcast i32 0 to i32 ; <i32> [#uses=0]
volatile store i32 0, i32* %v, align 4
%tmp1 = call i32 @_setjmp( %struct.__jmp_buf_tag* getelementptr ([1 x %struct.__jmp_buf_tag]* @j, i32 0, i32 0) ) ; <i32> [#uses=1]
%tmp2 = icmp ne i32 %tmp1, 0 ; <i1> [#uses=1]
%tmp23 = zext i1 %tmp2 to i8 ; <i8> [#uses=1]
%toBool = icmp ne i8 %tmp23, 0 ; <i1> [#uses=1]
br i1 %toBool, label %bb, label %bb5
bb: ; preds = %entry
%tmp4 = volatile load i32* %v, align 4 ; <i32> [#uses=1]
store i32 %tmp4, i32* %tmp, align 4
br label %bb6
bb5: ; preds = %entry
volatile store i32 1, i32* %v, align 4
call void @g( )
store i32 0, i32* %tmp, align 4
br label %bb6
bb6: ; preds = %bb5, %bb
%tmp7 = load i32* %tmp, align 4 ; <i32> [#uses=1]
store i32 %tmp7, i32* %retval, align 4
br label %return
return: ; preds = %bb6
%retval8 = load i32* %retval ; <i32> [#uses=1]
ret i32 %retval8
}
declare i32 @_setjmp(%struct.__jmp_buf_tag*)
declare void @g()