[PATCH] D146215: [BOLT] Reject symbols pointing to section end

[Job Noorman via Phabricator via llvm-commits]

jobnoorman updated this revision to Diff 506280.
jobnoorman added a comment.

Swap check with the `if (!Section->isText())` check as suggested by @yota9.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D146215/new/

https://reviews.llvm.org/D146215

Files:
  bolt/lib/Rewrite/RewriteInstance.cpp
  bolt/test/X86/section-end-sym.s


Index: bolt/test/X86/section-end-sym.s
===================================================================
--- /dev/null
+++ bolt/test/X86/section-end-sym.s
@@ -0,0 +1,29 @@
+## Check that BOLT doesn't consider end-of-section symbols (e.g., _etext) as
+## functions.
+
+# REQUIRES: system-linux
+
+# RUN: llvm-mc -filetype=obj -triple x86_64-unknown-linux %s -o %t.o
+# RUN: ld.lld %t.o -o %t.exe -q
+# RUN: llvm-bolt %t.exe -o /dev/null --print-cfg --debug-only=bolt 2>&1 \
+# RUN:   | FileCheck %s
+
+# CHECK: considering symbol etext for function
+# CHECK-NEXT: rejecting as symbol points to end of its section
+# CHECK-NOT: Binary Function "etext{{.*}}" after building cfg
+
+
+  .text
+  .globl _start
+  .type _start, at function
+_start:
+  retq
+  .size _start, .-_start
+
+  .align 0x1000
+  .globl etext
+etext:
+
+  .data
+.Lfoo:
+  .word 0
Index: bolt/lib/Rewrite/RewriteInstance.cpp
===================================================================
--- bolt/lib/Rewrite/RewriteInstance.cpp
+++ bolt/lib/Rewrite/RewriteInstance.cpp
@@ -1050,6 +1050,16 @@
     LLVM_DEBUG(dbgs() << "BOLT-DEBUG: considering symbol " << UniqueName
                       << " for function\n");
 
+    if (Address == Section->getAddress() + Section->getSize()) {
+      assert(SymbolSize == 0 &&
+             "unexpect non-zero sized symbol at end of section");
+      LLVM_DEBUG(
+          dbgs()
+          << "BOLT-DEBUG: rejecting as symbol points to end of its section\n");
+      registerName(SymbolSize);
+      continue;
+    }
+
     if (!Section->isText()) {
       assert(SymbolType != SymbolRef::ST_Function &&
              "unexpected function inside non-code section");


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