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authorH.J. Lu <hjl.tools@gmail.com>2018-09-13 06:12:31 -0700
committerH.J. Lu <hjl.tools@gmail.com>2018-09-13 06:12:31 -0700
commit79f0fa25b95fd82122ee76d61fded661cc3ece87 (patch)
tree6a00f3583a867b6f5e4a60ed2268801e03e8ead7
parent57f6375ec10415fc26bbfaf4fdc19effb313a06d (diff)
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x86: Swap destination/source to encode VEX only if possible
When encoding VEX, we can swap destination and source only if there are more than 1 register operand. * config/tc-i386.c (build_vex_prefix): Swap destination and source only if there are more than 1 register operand.
-rw-r--r--gas/ChangeLog5
-rw-r--r--gas/config/tc-i386.c7
2 files changed, 9 insertions, 3 deletions
diff --git a/gas/ChangeLog b/gas/ChangeLog
index 7a82555..fc17226 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,8 @@
+2018-09-13 H.J. Lu <hongjiu.lu@intel.com>
+
+ * config/tc-i386.c (build_vex_prefix): Swap destination and
+ source only if there are more than 1 register operand.
+
2018-09-13 Jan Beulich <jbeulich@suse.com>
* config/tc-i386.c (operand_size_match): Also deal with three
diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c
index 2bff48a..40b4583 100644
--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -3364,9 +3364,10 @@ build_vex_prefix (const insn_template *t)
else
register_specifier = 0xf;
- /* Use 2-byte VEX prefix by swapping destination and source
- operand. */
- if (i.vec_encoding != vex_encoding_vex3
+ /* Use 2-byte VEX prefix by swapping destination and source operand
+ if there are more than 1 register operand. */
+ if (i.reg_operands > 1
+ && i.vec_encoding != vex_encoding_vex3
&& i.dir_encoding == dir_encoding_default
&& i.operands == i.reg_operands
&& operand_type_equal (&i.types[0], &i.types[i.operands - 1])