[llvm] 155ac33 - [BuildLibCalls] Add noalias for strcat and stpcpy

[Dávid Bolvanský via llvm-commits]

Author: Dávid Bolvanský
Date: 2020-09-27T21:37:09+02:00
New Revision: 155ac333945d7af507bb28dc6f2539300a4c0666

URL: https://github.com/llvm/llvm-project/commit/155ac333945d7af507bb28dc6f2539300a4c0666
DIFF: https://github.com/llvm/llvm-project/commit/155ac333945d7af507bb28dc6f2539300a4c0666.diff

LOG: [BuildLibCalls] Add noalias for strcat and stpcpy

strcat:
destination and source shall not overlap. (http://www.cplusplus.com/reference/cstring/strcat/)

stpcpy:
The strings may not overlap, and the destination string dest must be  large enough to receive the copy. (https://man7.org/linux/man-pages/man3/stpcpy.3.html)

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D88335

Added: 
    

Modified: 
    llvm/lib/Transforms/Utils/BuildLibCalls.cpp
    llvm/test/Transforms/InferFunctionAttrs/annotate.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Utils/BuildLibCalls.cpp b/llvm/lib/Transforms/Utils/BuildLibCalls.cpp
index 09ed68a5f678..64e168d48da9 100644
--- a/llvm/lib/Transforms/Utils/BuildLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/BuildLibCalls.cpp
@@ -203,9 +203,6 @@ bool llvm::inferLibFuncAttributes(Function &F, const TargetLibraryInfo &TLI) {
     return Changed;
   case LibFunc_strcpy:
   case LibFunc_strncpy:
-    Changed |= setDoesNotAlias(F, 0);
-    Changed |= setDoesNotAlias(F, 1);
-    LLVM_FALLTHROUGH;
   case LibFunc_strcat:
   case LibFunc_strncat:
     Changed |= setReturnedArg(F, 0);
@@ -215,6 +212,8 @@ bool llvm::inferLibFuncAttributes(Function &F, const TargetLibraryInfo &TLI) {
     Changed |= setDoesNotThrow(F);
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setOnlyReadsMemory(F, 1);
+    Changed |= setDoesNotAlias(F, 0);
+    Changed |= setDoesNotAlias(F, 1);
     return Changed;
   case LibFunc_strxfrm:
     Changed |= setDoesNotThrow(F);

diff  --git a/llvm/test/Transforms/InferFunctionAttrs/annotate.ll b/llvm/test/Transforms/InferFunctionAttrs/annotate.ll
index 7f52bf771769..d4b0f0fb679d 100644
--- a/llvm/test/Transforms/InferFunctionAttrs/annotate.ll
+++ b/llvm/test/Transforms/InferFunctionAttrs/annotate.ll
@@ -825,16 +825,16 @@ declare i32 @statvfs(i8*, %opaque*)
 ; CHECK-LINUX: declare noundef i32 @statvfs64(i8* nocapture noundef readonly, %opaque* nocapture noundef) [[G1]]
 declare i32 @statvfs64(i8*, %opaque*)
 
-; CHECK: declare i8* @stpcpy(i8*, i8* nocapture readonly) [[G1]]
+; CHECK: declare i8* @stpcpy(i8* noalias, i8* noalias nocapture readonly) [[G1]]
 declare i8* @stpcpy(i8*, i8*)
 
-; CHECK: declare i8* @stpncpy(i8*, i8* nocapture readonly, i64) [[G1]]
+; CHECK: declare i8* @stpncpy(i8* noalias, i8* noalias nocapture readonly, i64) [[G1]]
 declare i8* @stpncpy(i8*, i8*, i64)
 
 ; CHECK: declare i32 @strcasecmp(i8* nocapture, i8* nocapture) [[G2]]
 declare i32 @strcasecmp(i8*, i8*)
 
-; CHECK: declare i8* @strcat(i8* returned, i8* nocapture readonly) [[G1]]
+; CHECK: declare i8* @strcat(i8* noalias returned, i8* noalias nocapture readonly) [[G1]]
 declare i8* @strcat(i8*, i8*)
 
 ; CHECK: declare i8* @strchr(i8*, i32) [[ARGMEMONLY_NOFREE_NOUNWIND_READONLY]]
@@ -861,7 +861,7 @@ declare i64 @strlen(i8*)
 ; CHECK: declare i32 @strncasecmp(i8* nocapture, i8* nocapture, i64) [[G2]]
 declare i32 @strncasecmp(i8*, i8*, i64)
 
-; CHECK: declare i8* @strncat(i8* returned, i8* nocapture readonly, i64) [[G1]]
+; CHECK: declare i8* @strncat(i8* noalias returned, i8* noalias nocapture readonly, i64) [[G1]]
 declare i8* @strncat(i8*, i8*, i64)
 
 ; CHECK: declare i32 @strncmp(i8* nocapture, i8* nocapture, i64) [[ARGMEMONLY_NOFREE_NOUNWIND_READONLY]]