[InstCombine] Missed optimization in math expression: sin(x) / cos(x) => tan(x)
Summary: This patch enables folding sin(x) / cos(x) -> tan(x), cos(x) / sin(x) -> 1 / tan(x) under -ffast-math flag
Reviewers: hfinkel, spatel
Reviewed By: spatel
Subscribers: andrew.w.kaylor, efriedma, scanon, llvm-commits
Differential Revision: https://reviews.llvm.org/D41286
llvm-svn: 322255
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
index 3860483..8abed5c 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -33,6 +33,7 @@
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/KnownBits.h"
#include "llvm/Transforms/InstCombine/InstCombineWorklist.h"
+#include "llvm/Transforms/Utils/BuildLibCalls.h"
#include <cassert>
#include <cstddef>
#include <cstdint>
@@ -1468,6 +1469,40 @@
}
}
+ if (AllowReassociate &&
+ Op0->hasOneUse() && Op1->hasOneUse()) {
+ Value *A;
+ // sin(a) / cos(a) -> tan(a)
+ if (match(Op0, m_Intrinsic<Intrinsic::sin>(m_Value(A))) &&
+ match(Op1, m_Intrinsic<Intrinsic::cos>(m_Specific(A)))) {
+ if (hasUnaryFloatFn(&TLI, I.getType(), LibFunc_tan,
+ LibFunc_tanf, LibFunc_tanl)) {
+ IRBuilder<> B(&I);
+ IRBuilder<>::FastMathFlagGuard Guard(B);
+ B.setFastMathFlags(I.getFastMathFlags());
+ Value *Tan = emitUnaryFloatFnCall(A, TLI.getName(LibFunc_tan),
+ B, I.getFunction()->getAttributes());
+ return replaceInstUsesWith(I, Tan);
+ }
+ }
+
+ // cos(a) / sin(a) -> 1/tan(a)
+ if (match(Op0, m_Intrinsic<Intrinsic::cos>(m_Value(A))) &&
+ match(Op1, m_Intrinsic<Intrinsic::sin>(m_Specific(A)))) {
+ if (hasUnaryFloatFn(&TLI, I.getType(), LibFunc_tan,
+ LibFunc_tanf, LibFunc_tanl)) {
+ IRBuilder<> B(&I);
+ IRBuilder<>::FastMathFlagGuard Guard(B);
+ B.setFastMathFlags(I.getFastMathFlags());
+ Value *Tan = emitUnaryFloatFnCall(A, TLI.getName(LibFunc_tan),
+ B, I.getFunction()->getAttributes());
+ Value *One = ConstantFP::get(Tan->getType(), 1.0);
+ Value *Div = B.CreateFDiv(One, Tan);
+ return replaceInstUsesWith(I, Div);
+ }
+ }
+ }
+
Value *LHS;
Value *RHS;