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

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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
This commit is contained in:
Roman Lebedev 2018-03-18 15:53:02 +00:00
parent 48886c59e8
commit 9134a6bbeb
2 changed files with 23 additions and 38 deletions
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9
lib/Transforms/InstCombine/InstCombineCompares.cpp
View File

@ -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.

52
test/Transforms/InstCombine/cast-unsigned-icmp-eqcmp-0.ll
View File

@ -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>