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fix a subtle volatile handling bug. 

llvm-svn: 50428
This commit is contained in:
Chris Lattner 2008-04-29 17:13:43 +00:00
parent a8197366db
commit 9233c124c9
2 changed files with 42 additions and 7 deletions
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19
llvm/lib/Transforms/Scalar/InstructionCombining.cpp
View File

@ -9432,16 +9432,21 @@ Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
// Insert and return the new operation.
if (CastInst* FirstCI = dyn_cast<CastInst>(FirstInst))
return CastInst::create(FirstCI->getOpcode(), PhiVal, PN.getType());
else if (isa<LoadInst>(FirstInst))
return new LoadInst(PhiVal, "", isVolatile);
else if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
return BinaryOperator::create(BinOp->getOpcode(), PhiVal, ConstantOp);
else if (CmpInst *CIOp = dyn_cast<CmpInst>(FirstInst))
if (CmpInst *CIOp = dyn_cast<CmpInst>(FirstInst))
return CmpInst::create(CIOp->getOpcode(), CIOp->getPredicate(),
PhiVal, ConstantOp);
else
assert(0 && "Unknown operation");
return 0;
assert(isa<LoadInst>(FirstInst) && "Unknown operation");
// If this was a volatile load that we are merging, make sure to loop through
// and mark all the input loads as non-volatile. If we don't do this, we will
// insert a new volatile load and the old ones will not be deletable.
if (isVolatile)
for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
cast<LoadInst>(PN.getIncomingValue(i))->setVolatile(false);
return new LoadInst(PhiVal, "", isVolatile);
}
/// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle

30
llvm/test/Transforms/InstCombine/2008-04-29-VolatileLoadMerge.ll Normal file
View File

@ -0,0 +1,30 @@
; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {volatile load} | count 1
; PR2262
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"
@g_1 = internal global i32 0 ; <i32*> [#uses=3]
@.str = internal constant [13 x i8] c"checksum = 0\00" ; <[13 x i8]*> [#uses=1]
@llvm.used = appending global [1 x i8*] [ i8* bitcast (i32 ()* @main to i8*) ], section "llvm.metadata" ; <[1 x i8*]*> [#uses=0]
define i32 @main() nounwind {
entry:
%tmp93 = icmp slt i32 0, 10 ; <i1> [#uses=0]
%tmp34 = volatile load i32* @g_1, align 4 ; <i32> [#uses=1]
br label %bb
bb: ; preds = %bb, %entry
%b.0.reg2mem.0 = phi i32 [ 0, %entry ], [ %tmp6, %bb ] ; <i32> [#uses=1]
%tmp3.reg2mem.0 = phi i32 [ %tmp34, %entry ], [ %tmp3, %bb ] ; <i32> [#uses=1]
%tmp4 = add i32 %tmp3.reg2mem.0, 5 ; <i32> [#uses=1]
volatile store i32 %tmp4, i32* @g_1, align 4
%tmp6 = add i32 %b.0.reg2mem.0, 1 ; <i32> [#uses=2]
%tmp9 = icmp slt i32 %tmp6, 10 ; <i1> [#uses=1]
%tmp3 = volatile load i32* @g_1, align 4 ; <i32> [#uses=1]
br i1 %tmp9, label %bb, label %bb11
bb11: ; preds = %bb
%tmp14 = call i32 @puts( i8* getelementptr ([13 x i8]* @.str, i32 0, i32 0) ) nounwind ; <i32> [#uses=0]
ret i32 0
}
declare i32 @puts(i8*)