x86-64: restrict by-imm31 optimization

Avoid changing the encoding when there's no size gain: If there's a REX
or REX2 prefix anyway and the base opcode wouldn't be changed, dropping
just REX.W / REX2.W has no (size) effect. (Same for the AND-by-imm7 case
in the same big conditional.)

While there also pull out the .qword check: For the 2-register-operands
case whether that's done on the 1st or 2nd operand doesn't matter. Due
to reduction in necessary parentheses this improves readability a tiny
bit.

diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c
index 4eb5655a384aad570e56679f0703320c7db4f5bd..9452b3c86bb1ac8eaac3bde8d542ed7f58cd562c 100644 (file)
--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -4809,8 +4809,8 @@ optimize_encoding (void)
     }
   else if (flag_code == CODE_64BIT
           && i.tm.opcode_space == SPACE_BASE
-          && ((i.types[1].bitfield.qword
-               && i.reg_operands == 1
+          && i.types[i.operands - 1].bitfield.qword
+          && ((i.reg_operands == 1
                && i.imm_operands == 1
                && i.op[0].imms->X_op == O_constant
                && ((i.tm.base_opcode == 0xb8
@@ -4818,26 +4818,29 @@ optimize_encoding (void)
                     && fits_in_unsigned_long (i.op[0].imms->X_add_number))
                    || (fits_in_imm31 (i.op[0].imms->X_add_number)
                        && (i.tm.base_opcode == 0x24
-                           || (i.tm.base_opcode == 0x80
-                               && i.tm.extension_opcode == 0x4)
-                           || i.tm.mnem_off == MN_test
+                           || (((i.tm.base_opcode == 0x80
+                                 && i.tm.extension_opcode == 0x4)
+                                || i.tm.mnem_off == MN_test)
+                               && !(i.op[1].regs->reg_flags
+                                    & (RegRex | RegRex2)))
                            || ((i.tm.base_opcode | 1) == 0xc7
                                && i.tm.extension_opcode == 0x0)))
                    || (fits_in_imm7 (i.op[0].imms->X_add_number)
                        && i.tm.base_opcode == 0x83
-                       && i.tm.extension_opcode == 0x4)))
-              || (i.types[0].bitfield.qword
-                  && ((i.reg_operands == 2
-                       && i.op[0].regs == i.op[1].regs
-                       && (i.tm.mnem_off == MN_xor
-                           || i.tm.mnem_off == MN_sub))
-                      || i.tm.mnem_off == MN_clr))))
+                       && i.tm.extension_opcode == 0x4
+                       && !(i.op[1].regs->reg_flags & (RegRex | RegRex2)))))
+              || ((i.reg_operands == 2
+                   && i.op[0].regs == i.op[1].regs
+                   && (i.tm.mnem_off == MN_xor
+                       || i.tm.mnem_off == MN_sub))
+                  || i.tm.mnem_off == MN_clr)))
     {
       /* Optimize: -O:
           andq $imm31, %r64   -> andl $imm31, %r32
           andq $imm7, %r64    -> andl $imm7, %r32
           testq $imm31, %r64  -> testl $imm31, %r32
           xorq %r64, %r64     -> xorl %r32, %r32
+          clrq %r64           -> clrl %r32
           subq %r64, %r64     -> subl %r32, %r32
           movq $imm31, %r64   -> movl $imm31, %r32
           movq $imm32, %r64   -> movl $imm32, %r32

diff --git a/gas/testsuite/gas/i386/x86-64-apx-ndd-optimize.d b/gas/testsuite/gas/i386/x86-64-apx-ndd-optimize.d
index 762d78be727335e103efd73d385f70aee2a2d71d..795dfcff126c31b7caa56cc8f0c1f5b81d63d858 100644 (file)
--- a/gas/testsuite/gas/i386/x86-64-apx-ndd-optimize.d
+++ b/gas/testsuite/gas/i386/x86-64-apx-ndd-optimize.d
@@ -35,7 +35,7 @@ Disassembly of section .text:
 \s*[a-f0-9]+:\s*62 7c 74 10 20 f9      and    %r15b,%r17b,%r17b
 \s*[a-f0-9]+:\s*4d 23 38               and    \(%r8\),%r15
 \s*[a-f0-9]+:\s*d5 49 23 04 07         and    \(%r15,%rax,1\),%r16
-\s*[a-f0-9]+:\s*d5 11 81 e6 34 12 00 00        and    \$0x1234,%r30d
+\s*[a-f0-9]+:\s*d5 19 81 e6 34 12 00 00        and    \$0x1234,%r30
 \s*[a-f0-9]+:\s*d5 1c 09 f9            or     %r15,%r17
 \s*[a-f0-9]+:\s*62 7c 74 10 08 f9      or     %r15b,%r17b,%r17b
 \s*[a-f0-9]+:\s*4d 0b 38               or     \(%r8\),%r15

diff --git a/gas/testsuite/gas/i386/x86-64-optimize-1.d b/gas/testsuite/gas/i386/x86-64-optimize-1.d
index 762fce977c66c537e5f163a729ca5e4cad95524f..b515d520afe6006e771dd2890fe5e100f78b591f 100644 (file)
--- a/gas/testsuite/gas/i386/x86-64-optimize-1.d
+++ b/gas/testsuite/gas/i386/x86-64-optimize-1.d
@@ -11,19 +11,19 @@ Disassembly of section .text:
  +[a-f0-9]+:   48 25 00 00 00 00       and    \$0x0,%rax       2: R_X86_64_32S foo
  +[a-f0-9]+:   25 ff ff ff 7f          and    \$0x7fffffff,%eax
  +[a-f0-9]+:   81 e3 ff ff ff 7f       and    \$0x7fffffff,%ebx
- +[a-f0-9]+:   41 81 e6 ff ff ff 7f    and    \$0x7fffffff,%r14d
+ +[a-f0-9]+:   49 81 e6 ff ff ff 7f    and    \$0x7fffffff,%r14
  +[a-f0-9]+:   48 25 00 00 00 80       and    \$0xffffffff80000000,%rax
  +[a-f0-9]+:   48 81 e3 00 00 00 80    and    \$0xffffffff80000000,%rbx
  +[a-f0-9]+:   49 81 e6 00 00 00 80    and    \$0xffffffff80000000,%r14
  +[a-f0-9]+:   83 e0 7f                and    \$0x7f,%eax
  +[a-f0-9]+:   83 e3 7f                and    \$0x7f,%ebx
- +[a-f0-9]+:   41 83 e6 7f             and    \$0x7f,%r14d
+ +[a-f0-9]+:   49 83 e6 7f             and    \$0x7f,%r14
  +[a-f0-9]+:   48 83 e0 80             and    \$0xffffffffffffff80,%rax
  +[a-f0-9]+:   48 83 e3 80             and    \$0xffffffffffffff80,%rbx
  +[a-f0-9]+:   49 83 e6 80             and    \$0xffffffffffffff80,%r14
  +[a-f0-9]+:   a9 ff ff ff 7f          test   \$0x7fffffff,%eax
  +[a-f0-9]+:   f7 c3 ff ff ff 7f       test   \$0x7fffffff,%ebx
- +[a-f0-9]+:   41 f7 c6 ff ff ff 7f    test   \$0x7fffffff,%r14d
+ +[a-f0-9]+:   49 f7 c6 ff ff ff 7f    test   \$0x7fffffff,%r14
  +[a-f0-9]+:   48 a9 00 00 00 80       test   \$0xffffffff80000000,%rax
  +[a-f0-9]+:   48 f7 c3 00 00 00 80    test   \$0xffffffff80000000,%rbx
  +[a-f0-9]+:   49 f7 c6 00 00 00 80    test   \$0xffffffff80000000,%r14

diff --git a/gas/testsuite/gas/i386/x86-64-optimize-3b.d b/gas/testsuite/gas/i386/x86-64-optimize-3b.d
index 929c6f70e8bf773813004cdab65a5e312b7c752e..476708a485aa125231393993f4e160e6b264011c 100644 (file)
--- a/gas/testsuite/gas/i386/x86-64-optimize-3b.d
+++ b/gas/testsuite/gas/i386/x86-64-optimize-3b.d
@@ -21,11 +21,11 @@ Disassembly of section .text:
  +[a-f0-9]+:   f7 c7 7f 00 00 00       test   \$0x7f,%edi
  +[a-f0-9]+:   66 f7 c7 7f 00          test   \$0x7f,%di
  +[a-f0-9]+:   40 f6 c7 7f             test   \$0x7f,%dil
- +[a-f0-9]+:   41 f7 c1 7f 00 00 00    test   \$0x7f,%r9d
+ +[a-f0-9]+:   49 f7 c1 7f 00 00 00    test   \$0x7f,%r9
  +[a-f0-9]+:   41 f7 c1 7f 00 00 00    test   \$0x7f,%r9d
  +[a-f0-9]+:   66 41 f7 c1 7f 00       test   \$0x7f,%r9w
  +[a-f0-9]+:   41 f6 c1 7f             test   \$0x7f,%r9b
- +[a-f0-9]+:   41 f7 c4 7f 00 00 00    test   \$0x7f,%r12d
+ +[a-f0-9]+:   49 f7 c4 7f 00 00 00    test   \$0x7f,%r12
  +[a-f0-9]+:   41 f7 c4 7f 00 00 00    test   \$0x7f,%r12d
  +[a-f0-9]+:   66 41 f7 c4 7f 00       test   \$0x7f,%r12w
  +[a-f0-9]+:   41 f6 c4 7f             test   \$0x7f,%r12b