mirror of
https://github.com/RPCS3/llvm-mirror.git
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2846a354a2
Summary:
`((%x * %y) u/ %x) != %y` is one of (3?) common ways to check that
some unsigned multiplication (will not) overflow.
Currently, we don't catch it. We could:
```
$ /repositories/alive2/build-Clang-unknown/alive -root-only ~/llvm-patch1.ll
Processing /home/lebedevri/llvm-patch1.ll..
----------------------------------------
Name: no overflow
%o0 = mul i4 %y, %x
%o1 = udiv i4 %o0, %x
%r = icmp ne i4 %o1, %y
ret i1 %r
=>
%n0 = umul_overflow i4 %x, %y
%o0 = extractvalue {i4, i1} %n0, 0
%o1 = udiv %o0, %x
%r = extractvalue {i4, i1} %n0, 1
ret %r
Done: 1
Optimization is correct!
----------------------------------------
Name: no overflow
%o0 = mul i4 %y, %x
%o1 = udiv i4 %o0, %x
%r = icmp eq i4 %o1, %y
ret i1 %r
=>
%n0 = umul_overflow i4 %x, %y
%o0 = extractvalue {i4, i1} %n0, 0
%o1 = udiv %o0, %x
%n1 = extractvalue {i4, i1} %n0, 1
%r = xor %n1, -1
ret i1 %r
Done: 1
Optimization is correct!
```
Reviewers: nikic, spatel, efriedma, xbolva00, RKSimon
Reviewed By: nikic
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65144
llvm-svn: 370348
168 lines
4.9 KiB
LLVM
168 lines
4.9 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt %s -instcombine -S | FileCheck %s
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; Fold
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; ((%x * %y) u/ %x) != %y
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; to
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; @llvm.umul.with.overflow(%x, %y) + extractvalue
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define i1 @t0_basic(i8 %x, i8 %y) {
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; CHECK-LABEL: @t0_basic(
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; CHECK-NEXT: [[UMUL:%.*]] = call { i8, i1 } @llvm.umul.with.overflow.i8(i8 [[X:%.*]], i8 [[Y:%.*]])
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; CHECK-NEXT: [[UMUL_OV:%.*]] = extractvalue { i8, i1 } [[UMUL]], 1
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; CHECK-NEXT: ret i1 [[UMUL_OV]]
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;
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%t0 = mul i8 %x, %y
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%t1 = udiv i8 %t0, %x
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%r = icmp ne i8 %t1, %y
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ret i1 %r
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}
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define <2 x i1> @t1_vec(<2 x i8> %x, <2 x i8> %y) {
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; CHECK-LABEL: @t1_vec(
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; CHECK-NEXT: [[UMUL:%.*]] = call { <2 x i8>, <2 x i1> } @llvm.umul.with.overflow.v2i8(<2 x i8> [[X:%.*]], <2 x i8> [[Y:%.*]])
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; CHECK-NEXT: [[UMUL_OV:%.*]] = extractvalue { <2 x i8>, <2 x i1> } [[UMUL]], 1
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; CHECK-NEXT: ret <2 x i1> [[UMUL_OV]]
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;
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%t0 = mul <2 x i8> %x, %y
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%t1 = udiv <2 x i8> %t0, %x
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%r = icmp ne <2 x i8> %t1, %y
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ret <2 x i1> %r
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}
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declare i8 @gen8()
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define i1 @t2_commutative(i8 %x) {
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; CHECK-LABEL: @t2_commutative(
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; CHECK-NEXT: [[Y:%.*]] = call i8 @gen8()
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; CHECK-NEXT: [[UMUL:%.*]] = call { i8, i1 } @llvm.umul.with.overflow.i8(i8 [[X:%.*]], i8 [[Y]])
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; CHECK-NEXT: [[UMUL_OV:%.*]] = extractvalue { i8, i1 } [[UMUL]], 1
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; CHECK-NEXT: ret i1 [[UMUL_OV]]
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;
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%y = call i8 @gen8()
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%t0 = mul i8 %y, %x ; swapped
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%t1 = udiv i8 %t0, %x
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%r = icmp ne i8 %t1, %y
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ret i1 %r
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}
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define i1 @t3_commutative(i8 %x) {
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; CHECK-LABEL: @t3_commutative(
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; CHECK-NEXT: [[Y:%.*]] = call i8 @gen8()
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; CHECK-NEXT: [[UMUL:%.*]] = call { i8, i1 } @llvm.umul.with.overflow.i8(i8 [[X:%.*]], i8 [[Y]])
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; CHECK-NEXT: [[UMUL_OV:%.*]] = extractvalue { i8, i1 } [[UMUL]], 1
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; CHECK-NEXT: ret i1 [[UMUL_OV]]
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;
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%y = call i8 @gen8()
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%t0 = mul i8 %y, %x ; swapped
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%t1 = udiv i8 %t0, %x
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%r = icmp ne i8 %t1, %y
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ret i1 %r
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}
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define i1 @t4_commutative(i8 %x) {
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; CHECK-LABEL: @t4_commutative(
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; CHECK-NEXT: [[Y:%.*]] = call i8 @gen8()
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; CHECK-NEXT: [[UMUL:%.*]] = call { i8, i1 } @llvm.umul.with.overflow.i8(i8 [[X:%.*]], i8 [[Y]])
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; CHECK-NEXT: [[UMUL_OV:%.*]] = extractvalue { i8, i1 } [[UMUL]], 1
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; CHECK-NEXT: ret i1 [[UMUL_OV]]
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;
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%y = call i8 @gen8()
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%t0 = mul i8 %y, %x ; swapped
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%t1 = udiv i8 %t0, %x
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%r = icmp ne i8 %y, %t1 ; swapped
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ret i1 %r
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}
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; Extra-use tests
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declare void @use8(i8)
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define i1 @t5_extrause0(i8 %x, i8 %y) {
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; CHECK-LABEL: @t5_extrause0(
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; CHECK-NEXT: [[UMUL:%.*]] = call { i8, i1 } @llvm.umul.with.overflow.i8(i8 [[X:%.*]], i8 [[Y:%.*]])
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; CHECK-NEXT: [[UMUL_VAL:%.*]] = extractvalue { i8, i1 } [[UMUL]], 0
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; CHECK-NEXT: [[UMUL_OV:%.*]] = extractvalue { i8, i1 } [[UMUL]], 1
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; CHECK-NEXT: call void @use8(i8 [[UMUL_VAL]])
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; CHECK-NEXT: ret i1 [[UMUL_OV]]
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;
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%t0 = mul i8 %x, %y
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call void @use8(i8 %t0)
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%t1 = udiv i8 %t0, %x
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%r = icmp ne i8 %t1, %y
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ret i1 %r
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}
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define i1 @t6_extrause1(i8 %x, i8 %y) {
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; CHECK-LABEL: @t6_extrause1(
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; CHECK-NEXT: [[T0:%.*]] = mul i8 [[X:%.*]], [[Y:%.*]]
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; CHECK-NEXT: [[T1:%.*]] = udiv i8 [[T0]], [[X]]
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; CHECK-NEXT: call void @use8(i8 [[T1]])
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; CHECK-NEXT: [[R:%.*]] = icmp ne i8 [[T1]], [[Y]]
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; CHECK-NEXT: ret i1 [[R]]
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;
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%t0 = mul i8 %x, %y
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%t1 = udiv i8 %t0, %x
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call void @use8(i8 %t1)
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%r = icmp ne i8 %t1, %y
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ret i1 %r
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}
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define i1 @t7_extrause2(i8 %x, i8 %y) {
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; CHECK-LABEL: @t7_extrause2(
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; CHECK-NEXT: [[T0:%.*]] = mul i8 [[X:%.*]], [[Y:%.*]]
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; CHECK-NEXT: call void @use8(i8 [[T0]])
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; CHECK-NEXT: [[T1:%.*]] = udiv i8 [[T0]], [[X]]
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; CHECK-NEXT: call void @use8(i8 [[T1]])
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; CHECK-NEXT: [[R:%.*]] = icmp ne i8 [[T1]], [[Y]]
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; CHECK-NEXT: ret i1 [[R]]
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;
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%t0 = mul i8 %x, %y
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call void @use8(i8 %t0)
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%t1 = udiv i8 %t0, %x
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call void @use8(i8 %t1)
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%r = icmp ne i8 %t1, %y
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ret i1 %r
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}
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; Negative tests
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define i1 @n8_different_x(i8 %x0, i8 %x1, i8 %y) {
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; CHECK-LABEL: @n8_different_x(
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; CHECK-NEXT: [[T0:%.*]] = mul i8 [[X0:%.*]], [[Y:%.*]]
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; CHECK-NEXT: [[T1:%.*]] = udiv i8 [[T0]], [[X1:%.*]]
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; CHECK-NEXT: [[R:%.*]] = icmp ne i8 [[T1]], [[Y]]
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; CHECK-NEXT: ret i1 [[R]]
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;
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%t0 = mul i8 %x0, %y
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%t1 = udiv i8 %t0, %x1
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%r = icmp ne i8 %t1, %y
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ret i1 %r
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}
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define i1 @n9_different_y(i8 %x, i8 %y0, i8 %y1) {
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; CHECK-LABEL: @n9_different_y(
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; CHECK-NEXT: [[T0:%.*]] = mul i8 [[X:%.*]], [[Y0:%.*]]
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; CHECK-NEXT: [[T1:%.*]] = udiv i8 [[T0]], [[X]]
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; CHECK-NEXT: [[R:%.*]] = icmp ne i8 [[T1]], [[Y1:%.*]]
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; CHECK-NEXT: ret i1 [[R]]
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;
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%t0 = mul i8 %x, %y0
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%t1 = udiv i8 %t0, %x
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%r = icmp ne i8 %t1, %y1
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ret i1 %r
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}
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define i1 @n10_wrong_pred(i8 %x, i8 %y) {
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; CHECK-LABEL: @n10_wrong_pred(
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; CHECK-NEXT: [[T0:%.*]] = mul i8 [[X:%.*]], [[Y:%.*]]
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; CHECK-NEXT: [[T1:%.*]] = udiv i8 [[T0]], [[X]]
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; CHECK-NEXT: [[R:%.*]] = icmp ugt i8 [[T1]], [[Y]]
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; CHECK-NEXT: ret i1 [[R]]
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;
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%t0 = mul i8 %x, %y
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%t1 = udiv i8 %t0, %x
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%r = icmp ugt i8 %t1, %y
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ret i1 %r
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}
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