[PATCH] D50180: [Sanitizers] Libasan failed to be build with -mthumb and -fno-omit-frame-pointer by GCC

[Denis Khalikov via Phabricator via llvm-commits]

denis13 updated this revision to Diff 164003.

https://reviews.llvm.org/D50180

Files:
  lib/sanitizer_common/sanitizer_linux.cc


Index: lib/sanitizer_common/sanitizer_linux.cc
===================================================================
--- lib/sanitizer_common/sanitizer_linux.cc
+++ lib/sanitizer_common/sanitizer_linux.cc
@@ -1597,7 +1597,10 @@
   register int *r2 __asm__("r2") = parent_tidptr;
   register void *r3 __asm__("r3") = newtls;
   register int *r4 __asm__("r4") = child_tidptr;
-  register int r7 __asm__("r7") = __NR_clone;
+  // GCC does not allow to have frame pointer register as a clobber register
+  // for inline assembler, when flag -fno-omit-frame-pointer is added. By
+  // default, arm with mthumb mode uses r7 as a frame pointer register.
+  register int r8 __asm__("r8") = __NR_clone;
 
 #if __ARM_ARCH > 4 || defined (__ARM_ARCH_4T__)
 # define ARCH_HAS_BX
@@ -1627,6 +1630,8 @@
 
                        /* Do the system call */
                        "swi 0x0\n"
+                       "push {r7}\n"
+                       "mov r7, r8\n"
 
                        /* if (%r0 != 0)
                         *   return %r0;
@@ -1642,9 +1647,10 @@
                        "mov r7, %7\n"
                        "swi 0x0\n"
                        "1:\n"
+                       "pop {r7}\n"
                        "mov %0, r0\n"
                        : "=r"(res)
-                       : "r"(r0), "r"(r1), "r"(r2), "r"(r3), "r"(r4), "r"(r7),
+                       : "r"(r0), "r"(r1), "r"(r2), "r"(r3), "r"(r4), "r"(r8),
                          "i"(__NR_exit)
                        : "memory");
   return res;


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