[llvm] r295353 - InstCombine: Canonicalize fast fmuladd to fmul + fadd

[Matt Arsenault via llvm-commits]

Author: arsenm
Date: Thu Feb 16 12:46:24 2017
New Revision: 295353

URL: http://llvm.org/viewvc/llvm-project?rev=295353&view=rev
Log:
InstCombine: Canonicalize fast fmuladd to fmul + fadd

Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp
    llvm/trunk/test/Transforms/InstCombine/fma.ll

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp?rev=295353&r1=295352&r2=295353&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp Thu Feb 16 12:46:24 2017
@@ -2044,8 +2044,21 @@ Instruction *InstCombiner::visitCallInst
       return replaceInstUsesWith(*II, V);
     break;
   }
-  case Intrinsic::fma:
   case Intrinsic::fmuladd: {
+    // Canonicalize fast fmuladd to the separate fmul + fadd.
+    if (II->hasUnsafeAlgebra()) {
+      BuilderTy::FastMathFlagGuard Guard(*Builder);
+      Builder->setFastMathFlags(II->getFastMathFlags());
+      Value *Mul = Builder->CreateFMul(II->getArgOperand(0),
+                                       II->getArgOperand(1));
+      Value *Add = Builder->CreateFAdd(Mul, II->getArgOperand(2));
+      Add->takeName(II);
+      return replaceInstUsesWith(*II, Add);
+    }
+
+    LLVM_FALLTHROUGH;
+  }
+  case Intrinsic::fma: {
     Value *Src0 = II->getArgOperand(0);
     Value *Src1 = II->getArgOperand(1);
 

Modified: llvm/trunk/test/Transforms/InstCombine/fma.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/fma.ll?rev=295353&r1=295352&r2=295353&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/fma.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/fma.ll Thu Feb 16 12:46:24 2017
@@ -78,7 +78,8 @@ define float @fmuladd_fneg_x_fneg_y(floa
 }
 
 ; CHECK-LABEL: @fmuladd_fneg_x_fneg_y_fast(
-; CHECK: %fmuladd = call fast float @llvm.fmuladd.f32(float %x, float %y, float %z)
+; CHECK-NEXT: %1 = fmul fast float %x, %y
+; CHECK-NEXT: %fmuladd = fadd fast float %1, %z
 define float @fmuladd_fneg_x_fneg_y_fast(float %x, float %y, float %z) {
   %x.fneg = fsub float -0.0, %x
   %y.fneg = fsub float -0.0, %y
@@ -122,7 +123,8 @@ define float @fmuladd_fabs_x_fabs_x(floa
 }
 
 ; CHECK-LABEL: @fmuladd_fabs_x_fabs_x_fast(
-; CHECK: %fmuladd = call fast float @llvm.fmuladd.f32(float %x, float %x, float %z)
+; CHECK-NEXT: %1 = fmul fast float %x, %x
+; CHECK-NEXT: %fmuladd = fadd fast float %1, %z
 define float @fmuladd_fabs_x_fabs_x_fast(float %x, float %z) {
   %x.fabs = call float @llvm.fabs.f32(float %x)
   %fmuladd = call fast float @llvm.fmuladd.f32(float %x.fabs, float %x.fabs, float %z)
@@ -144,7 +146,8 @@ define float @fma_k_y_z_fast(float %y, f
 }
 
 ; CHECK-LABEL: @fmuladd_k_y_z_fast(
-; CHECK: %fmuladd = call fast float @llvm.fmuladd.f32(float %y, float 4.000000e+00, float %z)
+; CHECK: %1 = fmul fast float %y, 4.000000e+00
+; CHECK-NEXT: %fmuladd = fadd fast float %1, %z
 define float @fmuladd_k_y_z_fast(float %y, float %z) {
   %fmuladd = call fast float @llvm.fmuladd.f32(float 4.0, float %y, float %z)
   ret float %fmuladd