llvm-project

Author SHA1 Message Date

Author	SHA1	Message	Date
Sanjay Patel	ee34d9b210	[InstCombine] use redirect of input file in regression tests; NFC This is a repeat of `1880092722` from 2009. We should have less risk of hitting bugs at this point because we auto-generate positive CHECK lines only, but this makes things consistent. Copying the original commit msg: "Change tests from "opt %s" to "opt < %s" so that opt doesn't see the input filename so that opt doesn't print the input filename in the output so that grep lines in the tests don't unintentionally match strings in the input filename."	2020-09-29 11:06:25 -04:00
Roman Lebedev	473a063a5e	[InstCombine] Fold '((%x * %y) u/ %x) != %y' to '@llvm.umul.with.overflow' + overflow bit extraction 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	2019-08-29 12:47:20 +00:00
Roman Lebedev	77d37037f0	[InstCombine][NFC] Tests for canonicalization of unsigned multiply overflow check llvm-svn: 366748	2019-07-22 22:08:45 +00:00

Sanjay Patel

ee34d9b210

[InstCombine] use redirect of input file in regression tests; NFC

This is a repeat of 1880092722 from 2009. We should have less risk
of hitting bugs at this point because we auto-generate positive CHECK
lines only, but this makes things consistent.

Copying the original commit msg:
"Change tests from "opt %s" to "opt < %s" so that opt doesn't see the
input filename so that opt doesn't print the input filename in the
output so that grep lines in the tests don't unintentionally match
strings in the input filename."

2020-09-29 11:06:25 -04:00

Roman Lebedev

473a063a5e

[InstCombine] Fold '((%x * %y) u/ %x) != %y' to '@llvm.umul.with.overflow' + overflow bit extraction

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

2019-08-29 12:47:20 +00:00

Roman Lebedev

77d37037f0

[InstCombine][NFC] Tests for canonicalization of unsigned multiply overflow check

llvm-svn: 366748

2019-07-22 22:08:45 +00:00

3 Commits