[profgen] Use a 64bit integer for &'ing the loadable address

[lanza]

For the linux kernel, the loadable segments start at 0xffff... and thus the 32 bit integer here was truncating all the meaningful bits. Grow it to 64 bits.

[llvmbot]

@llvm/pr-subscribers-pgo

Author: Nathan Lanza (lanza)

Changes

For the linux kernel, the loadable segments start at 0xffff... and thus the 32 bit integer here was truncating all the meaningful bits. Grow it to 64 bits.

---

Full diff: https://github.com/llvm/llvm-project/pull/79930.diff

1 Files Affected:

• (modified) llvm/tools/llvm-profgen/ProfiledBinary.cpp (+1-1)

diff --git a/llvm/tools/llvm-profgen/ProfiledBinary.cpp b/llvm/tools/llvm-profgen/ProfiledBinary.cpp
index b40c5f8cbbe068..f62228627b8f1e 100644
--- a/llvm/tools/llvm-profgen/ProfiledBinary.cpp
+++ b/llvm/tools/llvm-profgen/ProfiledBinary.cpp
@@ -317,7 +317,7 @@ void ProfiledBinary::setPreferredTextSegmentAddresses(const ELFFile<ELFT> &Obj,
   // However such info isn't available at post-processing time, assuming
   // 4K page now. Note that we don't use EXEC_PAGESIZE from <linux/param.h>
   // because we may build the tools on non-linux.
-  uint32_t PageSize = 0x1000;
+  uint64_t PageSize = 0x1000;
   for (const typename ELFT::Phdr &Phdr : PhdrRange) {
     if (Phdr.p_type == ELF::PT_LOAD) {
       if (!FirstLoadableAddress)

[WenleiHe]

Good catch! Thanks for the fix.

I'm wondering why we didn't run into the same issue when using llvm-profgen to generate profile for server linux kernel. cc @yonghong-song

[lanza]

Yea, no idea. The kernel on my work devserver also has a v_addr higher than 0xffffffff00000000, so this should have been truncating all along.