[RawProfReader]When constructing symbol table, read the MD5 of function name in the proper byte order

[mingmingl-llvm]

Before this patch, when the field NameRef is generated in little-endian systems and read back in big-endian systems, the information gets dropped.

• The bug gets caught by a buildbot https://lab.llvm.org/buildbot/#/builders/94/builds/17931 . In the test, two indirect call targets are not imported.

  ; IMPORTS-DAG: Import _Z7callee1v
              ^
<stdin>:1:1: note: scanning from here
main.ll: Import _Z11global_funcv from lib.cc
^
<stdin>:1:10: note: possible intended match here
main.ll: Import _Z11global_funcv from lib.cc
        ^
Input file: <stdin>
Check file: /home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/llvm/test/Transforms/PGOProfile/thinlto_indirect_call_promotion.ll
-dump-input=help explains the following input dump.
Input was:
<<<<<<
         1: main.ll: Import _Z11global_funcv from lib.cc 
dag:34'0     X~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ error: no match found
dag:34'1              ?                                    possible intended match

This commit (b399924#diff-b196b796c5a396c7cdf93b347fe47e2b29b72d0b7dd0e2b88abb964d376ee50e) gates the fix by flag and provide test data by creating big-endian profiles (rather than getting a real big-endian system).

• This is a hexdump of little-endian profile data, and this is the big-endian version of it.
• The README.md shows the result of llvm-profdata show -ic-targets before and after the fix when the profile is in big-endian.

[llvmbot]

@llvm/pr-subscribers-pgo

@llvm/pr-subscribers-llvm-transforms

Author: Mingming Liu (minglotus-6)

Changes

Before this patch, when the field NameRef is generated in little-endian systems and read back in big-endian systems, the information gets dropped.

This commit (b399924#diff-b196b796c5a396c7cdf93b347fe47e2b29b72d0b7dd0e2b88abb964d376ee50e) gates the fix by flag and provide test data by creating big-endian profiles (rather than getting a real big-endian system).

• This is a hexdump of little-endian profile data, and this is the big-endian version of it.
• The README.md shows the result of llvm-profdata show -ic-targets before and after the fix when the profile is in big-endian.

---

Full diff: https://github.com/llvm/llvm-project/pull/76312.diff

2 Files Affected:

• (modified) llvm/lib/ProfileData/InstrProfReader.cpp (+1-1)
• (modified) llvm/test/Transforms/PGOProfile/thinlto_indirect_call_promotion.ll (-3)

diff --git a/llvm/lib/ProfileData/InstrProfReader.cpp b/llvm/lib/ProfileData/InstrProfReader.cpp
index 8f62df79d5b7e8..b547cf7181b16a 100644
--- a/llvm/lib/ProfileData/InstrProfReader.cpp
+++ b/llvm/lib/ProfileData/InstrProfReader.cpp
@@ -539,7 +539,7 @@ Error RawInstrProfReader<IntPtrT>::createSymtab(InstrProfSymtab &Symtab) {
     const IntPtrT FPtr = swap(I->FunctionPointer);
     if (!FPtr)
       continue;
-    Symtab.mapAddress(FPtr, I->NameRef);
+    Symtab.mapAddress(FPtr, swap(I->NameRef));
   }
   return success();
 }
diff --git a/llvm/test/Transforms/PGOProfile/thinlto_indirect_call_promotion.ll b/llvm/test/Transforms/PGOProfile/thinlto_indirect_call_promotion.ll
index b24effed7024c2..d2f4696ccf41d7 100644
--- a/llvm/test/Transforms/PGOProfile/thinlto_indirect_call_promotion.ll
+++ b/llvm/test/Transforms/PGOProfile/thinlto_indirect_call_promotion.ll
@@ -9,9 +9,6 @@
 ; The raw profiles storesd compressed function names, so profile reader should
 ; be built with zlib support to decompress them.
 ; REQUIRES: zlib
-; REQUIRES: host-byteorder-little-endian
-; Raw profiles are generate on 64-bit systems.
-; REQUIRES: llvm-64-bits
 
 ; RUN: rm -rf %t && split-file %s %t && cd %t
 

[mingmingl-llvm]

thanks for the quick review @teresajohnson ! As discussed I added a pointer to buildbot in the description.