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Differential D100601

[InferAttrs] Do not mark first argument of str(n)cat as writeonly.
ClosedPublic

Authored by fhahn on Apr 15 2021, 2:40 PM.

Details

Reviewers
efriedma
xbolva00
jdoerfert
Commits
rG3e7ee5428d34: [InferAttrs] Do not mark first argument of str(n)cat as writeonly.
Summary

str(n)cat appends a copy of the second argument to the end of the first
argument. To find the end of the first argument, str(n)cat has to read
from it until it finds the terminating 0. So it should not be marked as
writeonly. I think this means the argument should not be marked as
writeonly.

(This is causing a mis-compile with legacy DSE (before it got removed))

Diff Detail

Event Timeline

fhahn created this revision.Apr 15 2021, 2:40 PM
Herald added a subscriber: hiraditya. · View Herald TranscriptApr 15 2021, 2:40 PM
fhahn requested review of this revision.Apr 15 2021, 2:40 PM
Herald added a project: Restricted Project. · View Herald TranscriptApr 15 2021, 2:40 PM
fhahn mentioned this in D89645: [InferAttrs] Add nocapture/writeonly to string/mem libcalls.Apr 15 2021, 2:42 PM
efriedma accepted this revision.Apr 15 2021, 2:45 PM

LGTM

This revision is now accepted and ready to land.Apr 15 2021, 2:45 PM
This revision was landed with ongoing or failed builds.Apr 15 2021, 3:00 PM
Closed by commit rG3e7ee5428d34: [InferAttrs] Do not mark first argument of str(n)cat as writeonly. (authored by fhahn). · Explain Why
This revision was automatically updated to reflect the committed changes.
fhahn added a commit: rG3e7ee5428d34: [InferAttrs] Do not mark first argument of str(n)cat as writeonly..
fhahn added a comment.Apr 15 2021, 3:01 PM

Thanks for taking a look! :)

Harbormaster completed remote builds in B99032: Diff 337910.Apr 15 2021, 3:46 PM

Revision Contents

PathSize
llvm/
lib/
Transforms/
Utils/
12 lines
test/
Transforms/
InferFunctionAttrs/
4 lines

Diff 337915

llvm/lib/Transforms/Utils/BuildLibCalls.cpp

Show First 20 Lines • Show All 251 Lines • ▼ Show 20 Linesbool llvm::inferLibFuncAttributes(Function &F, const TargetLibraryInfo &TLI) {
case LibFunc_strtoll: case LibFunc_strtoll:
case LibFunc_strtold: case LibFunc_strtold:
case LibFunc_strtoull: case LibFunc_strtoull:
Changed |= setDoesNotThrow(F); Changed |= setDoesNotThrow(F);
Changed |= setWillReturn(F); Changed |= setWillReturn(F);
Changed |= setDoesNotCapture(F, 1); Changed |= setDoesNotCapture(F, 1);
Changed |= setOnlyReadsMemory(F, 0); Changed |= setOnlyReadsMemory(F, 0);
return Changed; return Changed;
case LibFunc_strcpy:
case LibFunc_strncpy:
case LibFunc_strcat: case LibFunc_strcat:
case LibFunc_strncat: case LibFunc_strncat:
Changed |= setOnlyAccessesArgMemory(F);
Changed |= setDoesNotThrow(F);
Changed |= setWillReturn(F); Changed |= setWillReturn(F);
Changed |= setReturnedArg(F, 0); Changed |= setReturnedArg(F, 0);
Changed |= setDoesNotCapture(F, 1);
Changed |= setOnlyReadsMemory(F, 1);
Changed |= setDoesNotAlias(F, 0);
Changed |= setDoesNotAlias(F, 1);
return Changed;
case LibFunc_strcpy:
case LibFunc_strncpy:
Changed |= setReturnedArg(F, 0);
LLVM_FALLTHROUGH; LLVM_FALLTHROUGH;
case LibFunc_stpcpy: case LibFunc_stpcpy:
case LibFunc_stpncpy: case LibFunc_stpncpy:
Changed |= setOnlyAccessesArgMemory(F); Changed |= setOnlyAccessesArgMemory(F);
Changed |= setDoesNotThrow(F); Changed |= setDoesNotThrow(F);
Changed |= setWillReturn(F); Changed |= setWillReturn(F);
Changed |= setDoesNotCapture(F, 1); Changed |= setDoesNotCapture(F, 1);
Changed |= setOnlyWritesMemory(F, 0); Changed |= setOnlyWritesMemory(F, 0);
▲ Show 20 Lines • Show All 1,398 Lines • Show Last 20 Lines

llvm/test/Transforms/InferFunctionAttrs/annotate.ll

Show First 20 Lines • Show All 833 Lines • ▼ Show 20 Lines
declare i8* @stpcpy(i8*, i8*) declare i8* @stpcpy(i8*, i8*)
; CHECK: declare i8* @stpncpy(i8* noalias writeonly, i8* noalias nocapture readonly, i64) [[ARGMEMONLY_NOFREE_NOUNWIND_WILLRETURN]] ; CHECK: declare i8* @stpncpy(i8* noalias writeonly, i8* noalias nocapture readonly, i64) [[ARGMEMONLY_NOFREE_NOUNWIND_WILLRETURN]]
declare i8* @stpncpy(i8*, i8*, i64) declare i8* @stpncpy(i8*, i8*, i64)
; CHECK: declare i32 @strcasecmp(i8* nocapture, i8* nocapture) [[NOFREE_NOUNWIND_READONLY_WILLRETURN:#[0-9]+]] ; CHECK: declare i32 @strcasecmp(i8* nocapture, i8* nocapture) [[NOFREE_NOUNWIND_READONLY_WILLRETURN:#[0-9]+]]
declare i32 @strcasecmp(i8*, i8*) declare i32 @strcasecmp(i8*, i8*)
; CHECK: declare i8* @strcat(i8* noalias returned writeonly, i8* noalias nocapture readonly) [[ARGMEMONLY_NOFREE_NOUNWIND_WILLRETURN]] ; CHECK: declare i8* @strcat(i8* noalias returned, i8* noalias nocapture readonly) [[ARGMEMONLY_NOFREE_NOUNWIND_WILLRETURN]]
declare i8* @strcat(i8*, i8*) declare i8* @strcat(i8*, i8*)
; CHECK: declare i8* @strchr(i8*, i32) [[ARGMEMONLY_NOFREE_NOUNWIND_READONLY]] ; CHECK: declare i8* @strchr(i8*, i32) [[ARGMEMONLY_NOFREE_NOUNWIND_READONLY]]
declare i8* @strchr(i8*, i32) declare i8* @strchr(i8*, i32)
; CHECK: declare i32 @strcmp(i8* nocapture, i8* nocapture) [[ARGMEMONLY_NOFREE_NOUNWIND_READONLY]] ; CHECK: declare i32 @strcmp(i8* nocapture, i8* nocapture) [[ARGMEMONLY_NOFREE_NOUNWIND_READONLY]]
declare i32 @strcmp(i8*, i8*) declare i32 @strcmp(i8*, i8*)
Show All 10 Lines
declare i8* @strdup(i8*) declare i8* @strdup(i8*)
; CHECK: declare i64 @strlen(i8* nocapture) [[ARGMEMONLY_NOFREE_NOUNWIND_READONLY]] ; CHECK: declare i64 @strlen(i8* nocapture) [[ARGMEMONLY_NOFREE_NOUNWIND_READONLY]]
declare i64 @strlen(i8*) declare i64 @strlen(i8*)
; CHECK: declare i32 @strncasecmp(i8* nocapture, i8* nocapture, i64) [[NOFREE_NOUNWIND_READONLY_WILLRETURN]] ; CHECK: declare i32 @strncasecmp(i8* nocapture, i8* nocapture, i64) [[NOFREE_NOUNWIND_READONLY_WILLRETURN]]
declare i32 @strncasecmp(i8*, i8*, i64) declare i32 @strncasecmp(i8*, i8*, i64)
; CHECK: declare i8* @strncat(i8* noalias returned writeonly, i8* noalias nocapture readonly, i64) [[ARGMEMONLY_NOFREE_NOUNWIND_WILLRETURN]] ; CHECK: declare i8* @strncat(i8* noalias returned, i8* noalias nocapture readonly, i64) [[ARGMEMONLY_NOFREE_NOUNWIND_WILLRETURN]]
declare i8* @strncat(i8*, i8*, i64) declare i8* @strncat(i8*, i8*, i64)
; CHECK: declare i32 @strncmp(i8* nocapture, i8* nocapture, i64) [[ARGMEMONLY_NOFREE_NOUNWIND_READONLY]] ; CHECK: declare i32 @strncmp(i8* nocapture, i8* nocapture, i64) [[ARGMEMONLY_NOFREE_NOUNWIND_READONLY]]
declare i32 @strncmp(i8*, i8*, i64) declare i32 @strncmp(i8*, i8*, i64)
; CHECK: declare i8* @strncpy(i8* noalias returned writeonly, i8* noalias nocapture readonly, i64) [[ARGMEMONLY_NOFREE_NOUNWIND_WILLRETURN]] ; CHECK: declare i8* @strncpy(i8* noalias returned writeonly, i8* noalias nocapture readonly, i64) [[ARGMEMONLY_NOFREE_NOUNWIND_WILLRETURN]]
declare i8* @strncpy(i8*, i8*, i64) declare i8* @strncpy(i8*, i8*, i64)
▲ Show 20 Lines • Show All 156 Lines • Show Last 20 Lines