diff options
| -rw-r--r-- | llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp | 21 | ||||
| -rw-r--r-- | llvm/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-0.ll | 24 | ||||
| -rw-r--r-- | llvm/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-1.ll (renamed from llvm/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness.ll) | 10 |
3 files changed, 43 insertions, 12 deletions
diff --git a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp index e9976c59971..f44729204a8 100644 --- a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp +++ b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp @@ -1530,15 +1530,6 @@ namespace { ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond, IVStrideUse* &CondUse, const SCEVHandle* &CondStride) { - // Forgo this transformation if the condition has multiple uses. This is - // over-conservative, but simpler than alternatives. It guards against - // comparisons with a use that occurs earlier than the add instruction for the - // new stride index. See - // test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness.ll - // for an example of this situation. - if (!Cond->hasOneUse()) - return Cond; - if (StrideOrder.size() < 2 || IVUsesByStride[*CondStride].Users.size() != 1) return Cond; @@ -1653,6 +1644,18 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond, } } + // Forgo this transformation if it the increment happens to be + // unfortunately positioned after the condition, and the condition + // has multiple uses which prevent it from being moved immediately + // before the branch. See + // test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-*.ll + // for an example of this situation. + 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. ICmpInst *OldCond = Cond; diff --git a/llvm/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-0.ll b/llvm/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-0.ll new file mode 100644 index 00000000000..33b05221511 --- /dev/null +++ b/llvm/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-0.ll @@ -0,0 +1,24 @@ +; RUN: llvm-as < %s | llc --x86-asm-syntax=att | grep {cmpl \$4} +target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128" +target triple = "x86_64-apple-darwin9" + +; This is like change-compare-stride-trickiness-1.ll except the comparison +; happens before the relevant use, so the comparison stride can't be +; easily changed. + +define void @foo() { +entry: + br label %loop + +loop: + %indvar = phi i32 [ 0, %entry ], [ %i.2.0.us1534, %loop ] ; <i32> [#uses=1] + %i.2.0.us1534 = add i32 %indvar, 1 ; <i32> [#uses=3] + %tmp611.us1535 = icmp eq i32 %i.2.0.us1534, 4 ; <i1> [#uses=2] + %tmp623.us1538 = select i1 %tmp611.us1535, i32 6, i32 0 ; <i32> [#uses=0] + %tmp628.us1540 = shl i32 %i.2.0.us1534, 1 ; <i32> [#uses=1] + %tmp645646647.us1547 = sext i32 %tmp628.us1540 to i64 ; <i64> [#uses=0] + br i1 %tmp611.us1535, label %exit, label %loop + +exit: + ret void +} diff --git a/llvm/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness.ll b/llvm/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-1.ll index 9a54b7be1f5..06e231212ed 100644 --- a/llvm/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness.ll +++ b/llvm/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-1.ll @@ -1,7 +1,11 @@ -; RUN: llvm-as < %s | llc +; RUN: llvm-as < %s | llc --x86-asm-syntax=att | grep {cmpl \$8} target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128" target triple = "x86_64-apple-darwin9" +; This is like change-compare-stride-trickiness-0.ll except the comparison +; happens after the relevant use, so the comparison stride can be +; easily changed. + define void @foo() { entry: br label %loop @@ -9,10 +13,10 @@ entry: loop: %indvar = phi i32 [ 0, %entry ], [ %i.2.0.us1534, %loop ] ; <i32> [#uses=1] %i.2.0.us1534 = add i32 %indvar, 1 ; <i32> [#uses=3] - %tmp611.us1535 = icmp eq i32 %i.2.0.us1534, 4 ; <i1> [#uses=2] - %tmp623.us1538 = select i1 %tmp611.us1535, i32 6, i32 0 ; <i32> [#uses=0] %tmp628.us1540 = shl i32 %i.2.0.us1534, 1 ; <i32> [#uses=1] %tmp645646647.us1547 = sext i32 %tmp628.us1540 to i64 ; <i64> [#uses=0] + %tmp611.us1535 = icmp eq i32 %i.2.0.us1534, 4 ; <i1> [#uses=2] + %tmp623.us1538 = select i1 %tmp611.us1535, i32 6, i32 0 ; <i32> [#uses=0] br i1 %tmp611.us1535, label %exit, label %loop exit: |
