[llvm] r215200 - [LoopVectorizer] Enable support for floating-point subtraction reductions

[James Molloy]

Author: jamesm
Date: Fri Aug  8 07:41:08 2014
New Revision: 215200

URL: http://llvm.org/viewvc/llvm-project?rev=215200&view=rev
Log:
[LoopVectorizer] Enable support for floating-point subtraction reductions


Modified:
    llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp
    llvm/trunk/test/Transforms/LoopVectorize/float-reduction.ll

Modified: llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp?rev=215200&r1=215199&r2=215200&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp (original)
+++ llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp Fri Aug  8 07:41:08 2014
@@ -5136,7 +5136,7 @@ LoopVectorizationLegality::isReductionIn
                                             ReductionKind Kind,
                                             ReductionInstDesc &Prev) {
   bool FP = I->getType()->isFloatingPointTy();
-  bool FastMath = (FP && I->isCommutative() && I->isAssociative());
+  bool FastMath = FP && I->hasUnsafeAlgebra();
   switch (I->getOpcode()) {
   default:
     return ReductionInstDesc(false, I);
@@ -5158,6 +5158,7 @@ LoopVectorizationLegality::isReductionIn
     return ReductionInstDesc(Kind == RK_IntegerXor, I);
   case Instruction::FMul:
     return ReductionInstDesc(Kind == RK_FloatMult && FastMath, I);
+  case Instruction::FSub:
   case Instruction::FAdd:
     return ReductionInstDesc(Kind == RK_FloatAdd && FastMath, I);
   case Instruction::FCmp:

Modified: llvm/trunk/test/Transforms/LoopVectorize/float-reduction.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopVectorize/float-reduction.ll?rev=215200&r1=215199&r2=215200&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/LoopVectorize/float-reduction.ll (original)
+++ llvm/trunk/test/Transforms/LoopVectorize/float-reduction.ll Fri Aug  8 07:41:08 2014
@@ -23,3 +23,25 @@ for.body:
 for.end:                                          ; preds = %for.body
   ret float %add
 }
+
+;CHECK-LABEL: @foosub(
+;CHECK: fsub fast <4 x float>
+;CHECK: ret
+define float @foosub(float* nocapture %A, i32* nocapture %n) nounwind uwtable readonly ssp {
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %for.body, %entry
+  %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
+  %sum.04 = phi float [ 0.000000e+00, %entry ], [ %sub, %for.body ]
+  %arrayidx = getelementptr inbounds float* %A, i64 %indvars.iv
+  %0 = load float* %arrayidx, align 4
+  %sub = fsub fast float %sum.04, %0
+  %indvars.iv.next = add i64 %indvars.iv, 1
+  %lftr.wideiv = trunc i64 %indvars.iv.next to i32
+  %exitcond = icmp eq i32 %lftr.wideiv, 200
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:                                          ; preds = %for.body
+  ret float %sub
+}