Implement support for simplifying vector comparisons by 0.0 and 1.0 like we

do for scalars.  Patch contributed by Nicolas Capens

This also generalizes the previous xforms to work on long double, now that 
isExactlyValue works for long double.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@54653 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 27 insertions, 6 deletions

diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index eebb7cf82f..bdea6e40d2 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -2480,10 +2480,17 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) {
 
       // "In IEEE floating point, x*1 is not equivalent to x for nans.  However,
       // ANSI says we can drop signals, so we can do this anyway." (from GCC)
-      // We need a better interface for long double here.
-      if (Op1->getType() == Type::FloatTy || Op1->getType() == Type::DoubleTy)
-        if (Op1F->isExactlyValue(1.0))
-          return ReplaceInstUsesWith(I, Op0);  // Eliminate 'mul double %X, 1.0'
+      if (Op1F->isExactlyValue(1.0))
+        return ReplaceInstUsesWith(I, Op0);  // Eliminate 'mul double %X, 1.0'
+    } else if (isa<VectorType>(Op1->getType())) {
+      if (isa<ConstantAggregateZero>(Op1))
+        return ReplaceInstUsesWith(I, Op1);
+      
+      // As above, vector X*splat(1.0) -> X in all defined cases.
+      if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1))
+        if (ConstantFP *F = dyn_cast_or_null<ConstantFP>(Op1V->getSplatValue()))
+          if (F->isExactlyValue(1.0))
+            return ReplaceInstUsesWith(I, Op0);
     }
     
     if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
@@ -11636,3 +11643,4 @@ FunctionPass *llvm::createInstructionCombiningPass() {
   return new InstCombiner();
 }
 
+
diff --git a/test/Transforms/InstCombine/mul.ll b/test/Transforms/InstCombine/mul.ll
index 8e9ab8d421..1a74025434 100644
--- a/test/Transforms/InstCombine/mul.ll
+++ b/test/Transforms/InstCombine/mul.ll
@@ -1,7 +1,5 @@
 ; This test makes sure that mul instructions are properly eliminated.
-;
 ; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep mul
-; END.
 
 define i32 @test1(i32 %A) {
         %B = mul i32 %A, 1              ; <i32> [#uses=1]
@@ -78,3 +76,18 @@ define i32 @test12(i8 %a, i32 %b) {
         ret i32 %e
 }
 
+; PR2642
+define internal void @test13(<4 x float>*) {
+	load <4 x float>* %0, align 1
+	mul <4 x float> %2, < float 1.000000e+00, float 1.000000e+00, float 1.000000e+00, float 1.000000e+00 >
+	store <4 x float> %3, <4 x float>* %0, align 1
+	ret void
+}
+
+define internal void @test14(<4 x float>*) {
+	load <4 x float>* %0, align 1
+	mul <4 x float> %2, zeroinitializer
+	store <4 x float> %3, <4 x float>* %0, align 1
+	ret void
+}
+