[i386/debug] Fix insn prefix in tls_global_dynamic_64_<mode>

2018-06-25  Tom de Vries  <tdevries@suse.de>

	PR debug/86257
	* config/i386/i386.md (define_insn "*tls_global_dynamic_64_<mode>"):
	Use data16 instead of .byte for insn prefix.

	* gcc.target/i386/pr86257.c: New test.

From-SVN: r262006

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index f612c5b58c0bf2a176334f75fb18190945e1ed5c..f4df7442de43aafd7ccab88258fea31cf76fe260 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2018-06-25  Tom de Vries  <tdevries@suse.de>
+
+       PR debug/86257
+       * config/i386/i386.md (define_insn "*tls_global_dynamic_64_<mode>"):
+       Use data16 instead of .byte for insn prefix.
+
 2018-06-25  Andreas Krebbel  <krebbel@linux.ibm.com>
 
        PR C++/86082

diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index eb77ef3c08fb9bdd8d57de8f9420b6de1e564c96..6f2300057aa9f5387076a26189bd7baedf498a80 100644 (file)
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -14733,7 +14733,18 @@
   "TARGET_64BIT"
 {
   if (!TARGET_X32)
-    fputs (ASM_BYTE "0x66\n", asm_out_file);
+    /* The .loc directive has effect for 'the immediately following assembly
+       instruction'.  So for a sequence:
+         .loc f l
+         .byte x
+         insn1
+       the 'immediately following assembly instruction' is insn1.
+       We want to emit an insn prefix here, but if we use .byte (as shown in
+       'ELF Handling For Thread-Local Storage'), a preceding .loc will point
+       inside the insn sequence, rather than to the start.  After relaxation
+       of the sequence by the linker, the .loc might point inside an insn.
+       Use data16 prefix instead, which doesn't have this problem.  */
+    fputs ("\tdata16", asm_out_file);
   output_asm_insn
     ("lea{q}\t{%E1@tlsgd(%%rip), %%rdi|rdi, %E1@tlsgd[rip]}", operands);
   if (TARGET_SUN_TLS || flag_plt || !HAVE_AS_IX86_TLS_GET_ADDR_GOT)

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 4ca7d21f3eee5951c8cc1720d8e0ddf840ca3648..e8ab480febf48d6e87c818c2484006e7901a5e99 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2018-06-25  Tom de Vries  <tdevries@suse.de>
+
+       PR debug/86257
+       * gcc.target/i386/pr86257.c: New test.
+
 2018-06-25  Andreas Krebbel  <krebbel@linux.ibm.com>
 
        PR C++/86082

diff --git a/gcc/testsuite/gcc.target/i386/pr86257.c b/gcc/testsuite/gcc.target/i386/pr86257.c
new file mode 100644 (file)
index 0000000..3287c19
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr86257.c
@@ -0,0 +1,14 @@
+/* { dg-require-effective-target fpic } */
+/* { dg-require-effective-target tls } */
+/* { dg-options "-g -fPIC" } */
+
+__thread int i;
+
+void
+foo(void)
+{
+  i = 0;
+}
+
+/* { dg-final { scan-assembler "data16\[ \t\]*leaq" } } */
+/* { dg-final { scan-assembler-not "\.byte\[ \t\]*0x66\n\[ \t\]*leaq" } } */