Instruction::isAssociative() returns true for fmul/fadd if they are tagged "unsafe" mode.
Approved by: Eli and Michael.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168848 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/llvm/Instruction.h b/include/llvm/Instruction.h
index 22c8289..2c1d41c 100644
--- a/include/llvm/Instruction.h
+++ b/include/llvm/Instruction.h
@@ -253,7 +253,7 @@
///
/// In LLVM, the Add, Mul, And, Or, and Xor operators are associative.
///
- bool isAssociative() const { return isAssociative(getOpcode()); }
+ bool isAssociative() const;
static bool isAssociative(unsigned op);
/// isCommutative - Return true if the instruction is commutative:
diff --git a/lib/VMCore/Instruction.cpp b/lib/VMCore/Instruction.cpp
index 4208144..d93c1d7 100644
--- a/lib/VMCore/Instruction.cpp
+++ b/lib/VMCore/Instruction.cpp
@@ -468,6 +468,20 @@
Opcode == Add || Opcode == Mul;
}
+bool Instruction::isAssociative() const {
+ unsigned Opcode = getOpcode();
+ if (isAssociative(Opcode))
+ return true;
+
+ switch (Opcode) {
+ case FMul:
+ case FAdd:
+ return cast<FPMathOperator>(this)->hasUnsafeAlgebra();
+ default:
+ return false;
+ }
+}
+
/// isCommutative - Return true if the instruction is commutative:
///
/// Commutative operators satisfy: (x op y) === (y op x)
diff --git a/test/Transforms/InstCombine/fast-math.ll b/test/Transforms/InstCombine/fast-math.ll
new file mode 100644
index 0000000..4224140
--- /dev/null
+++ b/test/Transforms/InstCombine/fast-math.ll
@@ -0,0 +1,32 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+; testing-case "float fold(float a) { return 1.2f * a * 2.3f; }"
+; 1.2f and 2.3f is supposed to be fold.
+define float @fold(float %a) {
+fold:
+ %mul = fmul fast float %a, 0x3FF3333340000000
+ %mul1 = fmul fast float %mul, 0x4002666660000000
+ ret float %mul1
+; CHECK: fold
+; CHECK: fmul float %a, 0x4006147AE0000000
+}
+
+; Same testing-case as the one used in fold() except that the operators have
+; fixed FP mode.
+define float @notfold(float %a) {
+notfold:
+; CHECK: notfold
+; CHECK: %mul = fmul fast float %a, 0x3FF3333340000000
+ %mul = fmul fast float %a, 0x3FF3333340000000
+ %mul1 = fmul float %mul, 0x4002666660000000
+ ret float %mul1
+}
+
+define float @fold2(float %a) {
+notfold2:
+; CHECK: fold2
+; CHECK: fmul float %a, 0x4006147AE0000000
+ %mul = fmul float %a, 0x3FF3333340000000
+ %mul1 = fmul fast float %mul, 0x4002666660000000
+ ret float %mul1
+}