[compiler-rt] r333071 - [sanitizer] Reland "Be more accurate when calculating the previous instruction address on ARM."

[Igor Kudrin via llvm-commits]

Author: ikudrin
Date: Wed May 23 02:18:10 2018
New Revision: 333071

URL: http://llvm.org/viewvc/llvm-project?rev=333071&view=rev
Log:
[sanitizer] Reland "Be more accurate when calculating the previous instruction address on ARM."

Differential Revision: https://reviews.llvm.org/D46004

Modified:
    compiler-rt/trunk/lib/sanitizer_common/sanitizer_stacktrace.cc
    compiler-rt/trunk/lib/sanitizer_common/sanitizer_stacktrace.h

Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_stacktrace.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_stacktrace.cc?rev=333071&r1=333070&r2=333071&view=diff
==============================================================================
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_stacktrace.cc (original)
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_stacktrace.cc Wed May 23 02:18:10 2018
@@ -20,7 +20,8 @@ namespace __sanitizer {
 uptr StackTrace::GetNextInstructionPc(uptr pc) {
 #if defined(__mips__)
   return pc + 8;
-#elif defined(__powerpc__) || defined(__sparc__)
+#elif defined(__powerpc__) || defined(__sparc__) || defined(__arm__) || \
+    defined(__aarch64__)
   return pc + 4;
 #else
   return pc + 1;

Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_stacktrace.h
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_stacktrace.h?rev=333071&r1=333070&r2=333071&view=diff
==============================================================================
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_stacktrace.h (original)
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_stacktrace.h Wed May 23 02:18:10 2018
@@ -75,10 +75,11 @@ struct StackTrace {
 ALWAYS_INLINE
 uptr StackTrace::GetPreviousInstructionPc(uptr pc) {
 #if defined(__arm__)
-  // Cancel Thumb bit.
-  pc = pc & (~1);
-#endif
-#if defined(__powerpc__) || defined(__powerpc64__)
+  // T32 (Thumb) branch instructions might be 16 or 32 bit long,
+  // so we return (pc-2) in that case in order to be safe.
+  // For A32 mode we return (pc-4) because all instructions are 32 bit long.
+  return (pc - 3) & (~1);
+#elif defined(__powerpc__) || defined(__powerpc64__) || defined(__aarch64__)
   // PCs are always 4 byte aligned.
   return pc - 4;
 #elif defined(__sparc__) || defined(__mips__)