From: H.J. Lu <hjl.tools@gmail.com>
Date: Thu, 12 Dec 2019 19:57:03 +0000 (-0800)
Subject: i386: Add -mbranches-within-32B-boundaries
X-Git-Url: http://git.efficios.com/?p=deliverable%2Fbinutils-gdb.git;a=commitdiff_plain;h=76cf450b4ce818b298451619e80e041e6eb4ec24

i386: Add -mbranches-within-32B-boundaries

Add -mbranches-within-32B-boundaries to enable

-malign-branch-boundary=32
-malign-branch=jcc+fused+jmp
-malign-branch-prefix-size=5

	* config/tc-i386.c (OPTION_MBRANCHES_WITH_32B_BOUNDARIES): New.
	(md_longopts): Add -mbranches-within-32B-boundaries.
	(md_parse_option): Handle -mbranches-within-32B-boundaries.
	(md_show_usage): Add -mbranches-within-32B-boundaries.
---

diff --git a/gas/ChangeLog b/gas/ChangeLog
index 7b83a0abd1..c6f776c028 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,10 @@
+2019-12-12  H.J. Lu  <hongjiu.lu@intel.com>
+
+	* config/tc-i386.c (OPTION_MBRANCHES_WITH_32B_BOUNDARIES): New.
+	(md_longopts): Add -mbranches-within-32B-boundaries.
+	(md_parse_option): Handle -mbranches-within-32B-boundaries.
+	(md_show_usage): Add -mbranches-within-32B-boundaries.
+
 2019-12-12  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* config/tc-i386.c (_i386_insn): Add has_gotpc_tls_reloc.
diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c
index 41a6a0817a..6c71fc4d22 100644
--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -12000,6 +12000,7 @@ const char *md_shortopts = "qnO::";
 #define OPTION_MALIGN_BRANCH_BOUNDARY (OPTION_MD_BASE + 27)
 #define OPTION_MALIGN_BRANCH_PREFIX_SIZE (OPTION_MD_BASE + 28)
 #define OPTION_MALIGN_BRANCH (OPTION_MD_BASE + 29)
+#define OPTION_MBRANCHES_WITH_32B_BOUNDARIES (OPTION_MD_BASE + 30)
 
 struct option md_longopts[] =
 {
@@ -12038,6 +12039,7 @@ struct option md_longopts[] =
   {"malign-branch-boundary", required_argument, NULL, OPTION_MALIGN_BRANCH_BOUNDARY},
   {"malign-branch-prefix-size", required_argument, NULL, OPTION_MALIGN_BRANCH_PREFIX_SIZE},
   {"malign-branch", required_argument, NULL, OPTION_MALIGN_BRANCH},
+  {"mbranches-within-32B-boundaries", no_argument, NULL, OPTION_MBRANCHES_WITH_32B_BOUNDARIES},
   {"mamd64", no_argument, NULL, OPTION_MAMD64},
   {"mintel64", no_argument, NULL, OPTION_MINTEL64},
   {NULL, no_argument, NULL, 0}
@@ -12500,6 +12502,14 @@ md_parse_option (int c, const char *arg)
       free (saved);
       break;
 
+    case OPTION_MBRANCHES_WITH_32B_BOUNDARIES:
+      align_branch_power = 5;
+      align_branch_prefix_size = 5;
+      align_branch = (align_branch_jcc_bit
+		      | align_branch_fused_bit
+		      | align_branch_jmp_bit);
+      break;
+
     case OPTION_MAMD64:
       intel64 = 0;
       break;
@@ -12763,6 +12773,9 @@ md_show_usage (FILE *stream)
   -malign-branch-prefix-size=NUM (default: 5)\n\
                           align branches with NUM prefixes per instruction\n"));
   fprintf (stream, _("\
+  -mbranches-within-32B-boundaries\n\
+                          align branches within 32 byte boundary\n"));
+  fprintf (stream, _("\
   -mamd64                 accept only AMD64 ISA [default]\n"));
   fprintf (stream, _("\
   -mintel64               accept only Intel64 ISA\n"));
diff --git a/gas/doc/c-i386.texi b/gas/doc/c-i386.texi
index 74296e61f6..08f139cc15 100644
--- a/gas/doc/c-i386.texi
+++ b/gas/doc/c-i386.texi
@@ -449,6 +449,17 @@ This option specifies the maximum number of prefixes on an instruction
 to align branches.  @var{NUM} should be between 0 and 5.  The default
 @var{NUM} is 5.
 
+@cindex @samp{-mbranches-within-32B-boundaries} option, i386
+@cindex @samp{-mbranches-within-32B-boundaries} option, x86-64
+@item -mbranches-within-32B-boundaries
+This option aligns conditional jumps, fused conditional jumps and
+unconditional jumps within 32 byte boundary with up to 5 segment prefixes
+on an instruction.  It is equivalent to
+@option{-malign-branch-boundary=32}
+@option{-malign-branch=jcc+fused+jmp}
+@option{-malign-branch-prefix-size=5}.
+The default doesn't align branches.
+
 @cindex @samp{-mx86-used-note=} option, i386
 @cindex @samp{-mx86-used-note=} option, x86-64
 @item -mx86-used-note=@var{no}