From f53f07046b2cfcc92f66cc330a05ba6efd7a7f44 Mon Sep 17 00:00:00 2001
From: Chad Rosier <mcrosier@codeaurora.org>
Date: Tue, 11 Nov 2014 23:36:42 +0000
Subject: [PATCH] [Reassociate] Canonicalize negative constants out of
 expressions.

Add support for FDiv, which was regressed by the previous commit.

llvm-svn: 221738
---
 llvm/lib/Transforms/Scalar/Reassociate.cpp         |  3 +-
 .../Reassociate/canonicalize-neg-const.ll          | 48 ++++++++++++++++++++++
 2 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/llvm/lib/Transforms/Scalar/Reassociate.cpp b/llvm/lib/Transforms/Scalar/Reassociate.cpp
index 7cde3ab..a24d3d4 100644
--- a/llvm/lib/Transforms/Scalar/Reassociate.cpp
+++ b/llvm/lib/Transforms/Scalar/Reassociate.cpp
@@ -1955,7 +1955,8 @@ Instruction *Reassociate::canonicalizeNegConstExpr(Instruction *I) {
 
   // Must be a mul instruction.
   unsigned Opcode = I->getOpcode();
-  if (Opcode != Instruction::Mul && Opcode != Instruction::FMul)
+  if (Opcode != Instruction::Mul && Opcode != Instruction::FMul &&
+      Opcode != Instruction::FDiv)
     return nullptr;
 
   // Must have at least one constant operand.
diff --git a/llvm/test/Transforms/Reassociate/canonicalize-neg-const.ll b/llvm/test/Transforms/Reassociate/canonicalize-neg-const.ll
index 5ac8a1f..80f433a 100644
--- a/llvm/test/Transforms/Reassociate/canonicalize-neg-const.ll
+++ b/llvm/test/Transforms/Reassociate/canonicalize-neg-const.ll
@@ -108,3 +108,51 @@ define double @test8(double %x, double %y) {
   %add = fadd double %mul, %x
   ret double %add
 }
+
+; Canonicalize (x - -0.1234 / y)
+define double @test9(double %x, double %y) {
+; CHECK-LABEL: @test9
+; CHECK-NEXT: fdiv double 1.234000e-01, %y
+; CHECK-NEXT: fadd double %x, %div
+; CHECK-NEXT: ret double
+
+  %div = fdiv double -1.234000e-01, %y
+  %sub = fsub double %x, %div
+  ret double %sub
+}
+
+; Don't modify (-0.1234 / y - x)
+define double @test10(double %x, double %y) {
+; CHECK-LABEL: @test10
+; CHECK-NEXT: fdiv double -1.234000e-01, %y
+; CHECK-NEXT: fsub double %div, %x
+; CHECK-NEXT: ret double %sub
+
+  %div = fdiv double -1.234000e-01, %y
+  %sub = fsub double %div, %x
+  ret double %sub
+}
+
+; Canonicalize (-0.1234 / y + x) -> (x - 0.1234 / y)
+define double @test11(double %x, double %y) {
+; CHECK-LABEL: @test11
+; CHECK-NEXT: fdiv double 1.234000e-01, %y
+; CHECK-NEXT: fsub double %x, %div
+; CHECK-NEXT: ret double %add
+
+  %div = fdiv double -1.234000e-01, %y
+  %add = fadd double %div, %x
+  ret double %add
+}
+
+; Canonicalize (y / -0.1234 + x) -> (x - y / 0.1234)
+define double @test12(double %x, double %y) {
+; CHECK-LABEL: @test12
+; CHECK-NEXT: fdiv double %y, 1.234000e-01
+; CHECK-NEXT: fsub double %x, %div
+; CHECK-NEXT: ret double %add
+
+  %div = fdiv double %y, -1.234000e-01
+  %add = fadd double %div, %x
+  ret double %add
+}
-- 
2.7.4