From: David Bolvansky <david.bolvansky@gmail.com>
Date: Thu, 11 Jul 2019 10:55:04 +0000 (+0000)
Subject: [InstCombine] Reorder recently added/improved pow transformations
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=0f3d79f3e7958d4240616897d09e996245ac0f5c;p=llvm

[InstCombine] Reorder recently added/improved pow transformations

Changed cases are now faster with exp2.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@365758 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/Utils/SimplifyLibCalls.cpp b/lib/Transforms/Utils/SimplifyLibCalls.cpp
index b481d2b50a8..bc55e77c44f 100644
--- a/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -1471,6 +1471,9 @@ Value *LibCallSimplifier::optimizePow(CallInst *Pow, IRBuilder<> &B) {
   if (match(Base, m_FPOne()))
     return Base;
 
+  if (Value *Exp = replacePowWithExp(Pow, B))
+    return Exp;
+
   // powf(x, sitofp(e)) -> powi(x, e)
   // powf(x, uitofp(e)) -> powi(x, e)
   if (AllowApprox && (isa<SIToFPInst>(Expo) || isa<UIToFPInst>(Expo))) {
@@ -1486,9 +1489,6 @@ Value *LibCallSimplifier::optimizePow(CallInst *Pow, IRBuilder<> &B) {
       return createPowWithIntegerExponent(Base, NewExpo, M, B);
   }
 
-  if (Value *Exp = replacePowWithExp(Pow, B))
-    return Exp;
-
   // Evaluate special cases related to the exponent.
 
   // pow(x, -1.0) -> 1.0 / x
diff --git a/test/Transforms/InstCombine/pow_fp_int.ll b/test/Transforms/InstCombine/pow_fp_int.ll
index f89353cd707..372a9e11c1e 100644
--- a/test/Transforms/InstCombine/pow_fp_int.ll
+++ b/test/Transforms/InstCombine/pow_fp_int.ll
@@ -51,8 +51,10 @@ define double @pow_uitofp_double_const_base_fast(i31 %x) {
 
 define double @pow_sitofp_double_const_base_power_of_2_fast(i32 %x) {
 ; CHECK-LABEL: @pow_sitofp_double_const_base_power_of_2_fast(
-; CHECK-NEXT:    [[TMP1:%.*]] = call afn float @llvm.powi.f32(float 1.600000e+01, i32 [[X:%.*]])
-; CHECK-NEXT:    [[RES:%.*]] = fpext float [[TMP1]] to double
+; CHECK-NEXT:    [[SUBFP:%.*]] = sitofp i32 [[X:%.*]] to float
+; CHECK-NEXT:    [[MUL:%.*]] = fmul afn float [[SUBFP]], 4.000000e+00
+; CHECK-NEXT:    [[EXP2:%.*]] = call afn float @llvm.exp2.f32(float [[MUL]])
+; CHECK-NEXT:    [[RES:%.*]] = fpext float [[EXP2]] to double
 ; CHECK-NEXT:    ret double [[RES]]
 ;
   %subfp = sitofp i32 %x to float
@@ -63,9 +65,10 @@ define double @pow_sitofp_double_const_base_power_of_2_fast(i32 %x) {
 
 define double @pow_uitofp_const_base_power_of_2_fast(i31 %x) {
 ; CHECK-LABEL: @pow_uitofp_const_base_power_of_2_fast(
-; CHECK-NEXT:    [[TMP1:%.*]] = zext i31 [[X:%.*]] to i32
-; CHECK-NEXT:    [[TMP2:%.*]] = call afn float @llvm.powi.f32(float 1.600000e+01, i32 [[TMP1]])
-; CHECK-NEXT:    [[RES:%.*]] = fpext float [[TMP2]] to double
+; CHECK-NEXT:    [[SUBFP:%.*]] = uitofp i31 [[X:%.*]] to float
+; CHECK-NEXT:    [[MUL:%.*]] = fmul afn float [[SUBFP]], 4.000000e+00
+; CHECK-NEXT:    [[EXP2:%.*]] = call afn float @llvm.exp2.f32(float [[MUL]])
+; CHECK-NEXT:    [[RES:%.*]] = fpext float [[EXP2]] to double
 ; CHECK-NEXT:    ret double [[RES]]
 ;
   %subfp = uitofp i31 %x to float