diff options
| -rw-r--r-- | lib/Transforms/Scalar/LoopStrengthReduce.cpp | 9 | ||||
| -rw-r--r-- | test/Transforms/LoopStrengthReduce/2008-08-13-CmpStride.ll | 31 |
2 files changed, 39 insertions, 1 deletions
diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp index 3d82fd2..f47a5af 100644 --- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp +++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp @@ -1542,6 +1542,12 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond, Value *NewIncV = NULL; int64_t Scale = 1; + // Check stride constant and the comparision constant signs to detect + // overflow. + if (ICmpInst::isSignedPredicate(Predicate) && + (CmpVal & SignBit) != (CmpSSInt & SignBit)) + return Cond; + // Look for a suitable stride / iv as replacement. std::stable_sort(StrideOrder.begin(), StrideOrder.end(), StrideCompare()); for (unsigned i = 0, e = StrideOrder.size(); i != e; ++i) { @@ -1640,11 +1646,12 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond, // before the branch. See // test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-*.ll // for an example of this situation. - if (!Cond->hasOneUse()) + if (!Cond->hasOneUse()) { for (BasicBlock::iterator I = Cond, E = Cond->getParent()->end(); I != E; ++I) if (I == NewIncV) return Cond; + } if (NewCmpVal != CmpVal) { // Create a new compare instruction using new stride / iv. diff --git a/test/Transforms/LoopStrengthReduce/2008-08-13-CmpStride.ll b/test/Transforms/LoopStrengthReduce/2008-08-13-CmpStride.ll new file mode 100644 index 0000000..fbd3c1e --- /dev/null +++ b/test/Transforms/LoopStrengthReduce/2008-08-13-CmpStride.ll @@ -0,0 +1,31 @@ +; RUN: llvm-as < %s | opt -loop-reduce | llvm-dis | grep add | count 2 +; PR 2662 +@g_3 = common global i16 0 ; <i16*> [#uses=2] +@"\01LC" = internal constant [4 x i8] c"%d\0A\00" ; <[4 x i8]*> [#uses=1] + +define void @func_1() nounwind { +entry: + br label %bb + +bb: ; preds = %bb, %entry + %l_2.0.reg2mem.0 = phi i16 [ 0, %entry ], [ %t1, %bb ] ; <i16> [#uses=2] + %t0 = shl i16 %l_2.0.reg2mem.0, 1 ; <i16>:0 [#uses=1] + volatile store i16 %t0, i16* @g_3, align 2 + %t1 = add i16 %l_2.0.reg2mem.0, -3 ; <i16>:1 [#uses=2] + %t2 = icmp slt i16 %t1, 1 ; <i1>:2 [#uses=1] + br i1 %t2, label %bb, label %return + +return: ; preds = %bb + ret void +} + +define i32 @main() nounwind { +entry: + tail call void @func_1( ) nounwind + volatile load i16* @g_3, align 2 ; <i16>:0 [#uses=1] + zext i16 %0 to i32 ; <i32>:1 [#uses=1] + tail call i32 (i8*, ...)* @printf( i8* getelementptr ([4 x i8]* @"\01LC", i32 0, i32 0), i32 %1 ) nounwind ; <i32>:2 [#uses=0] + ret i32 0 +} + +declare i32 @printf(i8*, ...) nounwind |