InstCombine: Add fma + fabs/fneg transforms

fma (fneg x), (fneg y), z -> fma x, y, z
fma (fabs x), (fabs x), z -> fma x, x, z

llvm-svn: 290859

1 files changed, 30 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 92369bd70b1..029976e3133 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -1581,6 +1581,36 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
       return replaceInstUsesWith(*II, V);
     break;
   }
+  case Intrinsic::fma:
+  case Intrinsic::fmuladd: {
+    Value *LHS = nullptr;
+    Value *RHS = nullptr;
+
+    Value *Src0 = II->getArgOperand(0);
+    Value *Src1 = II->getArgOperand(1);
+
+    // fma fneg(x), fneg(y), z -> fma x, y, z
+    if (match(Src0, m_FNeg(m_Value(LHS))) &&
+        match(Src1, m_FNeg(m_Value(RHS)))) {
+      CallInst *NewCall = Builder->CreateCall(II->getCalledFunction(),
+                                              {LHS, RHS, II->getArgOperand(2)});
+      NewCall->takeName(II);
+      NewCall->copyFastMathFlags(II);
+      return replaceInstUsesWith(*II, NewCall);
+    }
+
+    // fma fabs(x), fabs(x), z -> fma x, x, z
+    if (match(Src0, m_Intrinsic<Intrinsic::fabs>(m_Value(LHS))) &&
+        match(Src1, m_Intrinsic<Intrinsic::fabs>(m_Value(RHS))) && LHS == RHS) {
+      CallInst *NewCall = Builder->CreateCall(II->getCalledFunction(),
+                                              {LHS, LHS, II->getArgOperand(2)});
+      NewCall->takeName(II);
+      NewCall->copyFastMathFlags(II);
+      return replaceInstUsesWith(*II, NewCall);
+    }
+
+    break;
+  }
   case Intrinsic::ppc_altivec_lvx:
   case Intrinsic::ppc_altivec_lvxl:
     // Turn PPC lvx -> load if the pointer is known aligned.