From: Roman Lebedev <lebedev.ri@gmail.com>
Date: Sun, 18 Mar 2018 15:53:02 +0000 (+0000)
Subject: [InstCombine] peek through unsigned FP casts for zero-equality compares (PR36682)
X-Git-Tag: llvmorg-7.0.0-rc1~10337
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=e6da3063a54c801eab5ff3ab267341a4804f9e4b;p=platform%2Fupstream%2Fllvm.git

[InstCombine] peek through unsigned FP casts for zero-equality compares (PR36682)

Summary:
This pattern came up in PR36682 / D44390
https://bugs.llvm.org/show_bug.cgi?id=36682
https://reviews.llvm.org/D44390
https://godbolt.org/g/oKvT5H

See also D44416

Reviewers: spatel, majnemer, efriedma, arsenm

Reviewed By: spatel

Subscribers: wdng, llvm-commits

Differential Revision: https://reviews.llvm.org/D44424

llvm-svn: 327799
---

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 0cd72bc..12894b7 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -4506,6 +4506,15 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
         return New;
   }
 
+  Value *X;
+
+  // Zero-equality checks are preserved through unsigned floating-point casts:
+  // icmp eq (bitcast (uitofp X)), 0 --> icmp eq X, 0
+  // icmp ne (bitcast (uitofp X)), 0 --> icmp ne X, 0
+  if (match(Op0, m_BitCast(m_UIToFP(m_Value(X)))))
+    if (I.isEquality() && match(Op1, m_Zero()))
+      return new ICmpInst(Pred, X, ConstantInt::getNullValue(X->getType()));
+
   // Test to see if the operands of the icmp are casted versions of other
   // values.  If the ptr->ptr cast can be stripped off both arguments, we do so
   // now.
diff --git a/llvm/test/Transforms/InstCombine/cast-unsigned-icmp-eqcmp-0.ll b/llvm/test/Transforms/InstCombine/cast-unsigned-icmp-eqcmp-0.ll
index f543883..dde3174 100644
--- a/llvm/test/Transforms/InstCombine/cast-unsigned-icmp-eqcmp-0.ll
+++ b/llvm/test/Transforms/InstCombine/cast-unsigned-icmp-eqcmp-0.ll
@@ -1,18 +1,16 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt < %s -instcombine -S | FileCheck %s
 
-; target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
-
 ; This is related to https://bugs.llvm.org/show_bug.cgi?id=36682
 
 ; FIXME: *all* of these are true tests.
 ; In *all* of these, uitofp and bitcast should be instcombine'd out.
 
+; FIXME: icmp eq/ne does not ignore undef elements in vectors.
+
 define i1 @i32_cast_cmp_eq_int_0_uitofp_float(i32 %i) {
 ; CHECK-LABEL: @i32_cast_cmp_eq_int_0_uitofp_float(
-; CHECK-NEXT:    [[F:%.*]] = uitofp i32 [[I:%.*]] to float
-; CHECK-NEXT:    [[B:%.*]] = bitcast float [[F]] to i32
-; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[B]], 0
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[I:%.*]], 0
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %f = uitofp i32 %i to float
@@ -23,9 +21,7 @@ define i1 @i32_cast_cmp_eq_int_0_uitofp_float(i32 %i) {
 
 define <2 x i1> @i32_cast_cmp_eq_int_0_uitofp_float_vec(<2 x i32> %i) {
 ; CHECK-LABEL: @i32_cast_cmp_eq_int_0_uitofp_float_vec(
-; CHECK-NEXT:    [[F:%.*]] = uitofp <2 x i32> [[I:%.*]] to <2 x float>
-; CHECK-NEXT:    [[B:%.*]] = bitcast <2 x float> [[F]] to <2 x i32>
-; CHECK-NEXT:    [[CMP:%.*]] = icmp eq <2 x i32> [[B]], zeroinitializer
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq <2 x i32> [[I:%.*]], zeroinitializer
 ; CHECK-NEXT:    ret <2 x i1> [[CMP]]
 ;
   %f = uitofp <2 x i32> %i to  <2 x float>
@@ -49,9 +45,7 @@ define <3 x i1> @i32_cast_cmp_eq_int_0_uitofp_float_vec_undef(<3 x i32> %i) {
 
 define i1 @i32_cast_cmp_ne_int_0_uitofp_float(i32 %i) {
 ; CHECK-LABEL: @i32_cast_cmp_ne_int_0_uitofp_float(
-; CHECK-NEXT:    [[F:%.*]] = uitofp i32 [[I:%.*]] to float
-; CHECK-NEXT:    [[B:%.*]] = bitcast float [[F]] to i32
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i32 [[B]], 0
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i32 [[I:%.*]], 0
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %f = uitofp i32 %i to float
@@ -62,9 +56,7 @@ define i1 @i32_cast_cmp_ne_int_0_uitofp_float(i32 %i) {
 
 define <2 x i1> @i32_cast_cmp_ne_int_0_uitofp_float_vec(<2 x i32> %i) {
 ; CHECK-LABEL: @i32_cast_cmp_ne_int_0_uitofp_float_vec(
-; CHECK-NEXT:    [[F:%.*]] = uitofp <2 x i32> [[I:%.*]] to <2 x float>
-; CHECK-NEXT:    [[B:%.*]] = bitcast <2 x float> [[F]] to <2 x i32>
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ne <2 x i32> [[B]], zeroinitializer
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ne <2 x i32> [[I:%.*]], zeroinitializer
 ; CHECK-NEXT:    ret <2 x i1> [[CMP]]
 ;
   %f = uitofp <2 x i32> %i to  <2 x float>
@@ -88,9 +80,7 @@ define <3 x i1> @i32_cast_cmp_ne_int_0_uitofp_float_vec_undef(<3 x i32> %i) {
 
 define i1 @i32_cast_cmp_eq_int_0_uitofp_double(i32 %i) {
 ; CHECK-LABEL: @i32_cast_cmp_eq_int_0_uitofp_double(
-; CHECK-NEXT:    [[F:%.*]] = uitofp i32 [[I:%.*]] to double
-; CHECK-NEXT:    [[B:%.*]] = bitcast double [[F]] to i64
-; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i64 [[B]], 0
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[I:%.*]], 0
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %f = uitofp i32 %i to double
@@ -101,9 +91,7 @@ define i1 @i32_cast_cmp_eq_int_0_uitofp_double(i32 %i) {
 
 define <2 x i1> @i32_cast_cmp_eq_int_0_uitofp_double_vec(<2 x i32> %i) {
 ; CHECK-LABEL: @i32_cast_cmp_eq_int_0_uitofp_double_vec(
-; CHECK-NEXT:    [[F:%.*]] = uitofp <2 x i32> [[I:%.*]] to <2 x double>
-; CHECK-NEXT:    [[B:%.*]] = bitcast <2 x double> [[F]] to <2 x i64>
-; CHECK-NEXT:    [[CMP:%.*]] = icmp eq <2 x i64> [[B]], zeroinitializer
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq <2 x i32> [[I:%.*]], zeroinitializer
 ; CHECK-NEXT:    ret <2 x i1> [[CMP]]
 ;
   %f = uitofp <2 x i32> %i to  <2 x double>
@@ -127,9 +115,7 @@ define <3 x i1> @i32_cast_cmp_eq_int_0_uitofp_double_vec_undef(<3 x i32> %i) {
 
 define i1 @i32_cast_cmp_ne_int_0_uitofp_double(i32 %i) {
 ; CHECK-LABEL: @i32_cast_cmp_ne_int_0_uitofp_double(
-; CHECK-NEXT:    [[F:%.*]] = uitofp i32 [[I:%.*]] to double
-; CHECK-NEXT:    [[B:%.*]] = bitcast double [[F]] to i64
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i64 [[B]], 0
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i32 [[I:%.*]], 0
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %f = uitofp i32 %i to double
@@ -140,9 +126,7 @@ define i1 @i32_cast_cmp_ne_int_0_uitofp_double(i32 %i) {
 
 define <2 x i1> @i32_cast_cmp_ne_int_0_uitofp_double_vec(<2 x i32> %i) {
 ; CHECK-LABEL: @i32_cast_cmp_ne_int_0_uitofp_double_vec(
-; CHECK-NEXT:    [[F:%.*]] = uitofp <2 x i32> [[I:%.*]] to <2 x double>
-; CHECK-NEXT:    [[B:%.*]] = bitcast <2 x double> [[F]] to <2 x i64>
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ne <2 x i64> [[B]], zeroinitializer
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ne <2 x i32> [[I:%.*]], zeroinitializer
 ; CHECK-NEXT:    ret <2 x i1> [[CMP]]
 ;
   %f = uitofp <2 x i32> %i to  <2 x double>
@@ -166,9 +150,7 @@ define <3 x i1> @i32_cast_cmp_ne_int_0_uitofp_double_vec_undef(<3 x i32> %i) {
 
 define i1 @i32_cast_cmp_eq_int_0_uitofp_half(i32 %i) {
 ; CHECK-LABEL: @i32_cast_cmp_eq_int_0_uitofp_half(
-; CHECK-NEXT:    [[F:%.*]] = uitofp i32 [[I:%.*]] to half
-; CHECK-NEXT:    [[B:%.*]] = bitcast half [[F]] to i16
-; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i16 [[B]], 0
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[I:%.*]], 0
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %f = uitofp i32 %i to half
@@ -179,9 +161,7 @@ define i1 @i32_cast_cmp_eq_int_0_uitofp_half(i32 %i) {
 
 define <2 x i1> @i32_cast_cmp_eq_int_0_uitofp_half_vec(<2 x i32> %i) {
 ; CHECK-LABEL: @i32_cast_cmp_eq_int_0_uitofp_half_vec(
-; CHECK-NEXT:    [[F:%.*]] = uitofp <2 x i32> [[I:%.*]] to <2 x half>
-; CHECK-NEXT:    [[B:%.*]] = bitcast <2 x half> [[F]] to <2 x i16>
-; CHECK-NEXT:    [[CMP:%.*]] = icmp eq <2 x i16> [[B]], zeroinitializer
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq <2 x i32> [[I:%.*]], zeroinitializer
 ; CHECK-NEXT:    ret <2 x i1> [[CMP]]
 ;
   %f = uitofp <2 x i32> %i to  <2 x half>
@@ -205,9 +185,7 @@ define <3 x i1> @i32_cast_cmp_eq_int_0_uitofp_half_vec_undef(<3 x i32> %i) {
 
 define i1 @i32_cast_cmp_ne_int_0_uitofp_half(i32 %i) {
 ; CHECK-LABEL: @i32_cast_cmp_ne_int_0_uitofp_half(
-; CHECK-NEXT:    [[F:%.*]] = uitofp i32 [[I:%.*]] to half
-; CHECK-NEXT:    [[B:%.*]] = bitcast half [[F]] to i16
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i16 [[B]], 0
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i32 [[I:%.*]], 0
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %f = uitofp i32 %i to half
@@ -218,9 +196,7 @@ define i1 @i32_cast_cmp_ne_int_0_uitofp_half(i32 %i) {
 
 define <2 x i1> @i32_cast_cmp_ne_int_0_uitofp_half_vec(<2 x i32> %i) {
 ; CHECK-LABEL: @i32_cast_cmp_ne_int_0_uitofp_half_vec(
-; CHECK-NEXT:    [[F:%.*]] = uitofp <2 x i32> [[I:%.*]] to <2 x half>
-; CHECK-NEXT:    [[B:%.*]] = bitcast <2 x half> [[F]] to <2 x i16>
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ne <2 x i16> [[B]], zeroinitializer
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ne <2 x i32> [[I:%.*]], zeroinitializer
 ; CHECK-NEXT:    ret <2 x i1> [[CMP]]
 ;
   %f = uitofp <2 x i32> %i to  <2 x half>