x86: refine special casing of insns with MSR as immediate

PR gas/34028

i.op[].imms is legitimate to de-reference only when the operand actually
is an immediate. The pointer happens to be non-NULL for most other operand
kinds (i.e. a deref is UB, but would likely not fault), just not for
memory operands without displacement.

Leverage that the to-be-special-cased insns all only have just a single
immediate, and leverage further that after the immediately preceding
swapping of operands valid immediates will come first. Hence the
conditional can be adjusted to satisfy the criteria above, and no loop is
needed at all.

With the conditional changed, leverage the property also in optimize_imm()
itself, reducing the number of loop iterations.

diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c
index bc759b2573a904e1cb8d760b919d7f339c87d96e..fb77f43126bf1d66dab91643b98acf66cd6757e7 100644 (file)
--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -7305,7 +7305,9 @@ i386_assemble (char *line)
          && i.imm_operands && i.operands > i.imm_operands))
       swap_2_operands (0, 1);
 
-  if (i.imm_operands)
+  /* All legitimate immediates are placed first now.  Others, if any, will be
+     rejected by match_template() anyway.  */
+  if (operand_type_check (i.types[0], imm))
     {
       /* For USER_MSR and MSR_IMM instructions, imm32 stands for the name of a
         model specific register (MSR). That's an unsigned quantity, whereas all
@@ -7315,10 +7317,7 @@ i386_assemble (char *line)
       if (is_cpu(current_templates.start, CpuUSER_MSR)
          || t->mnem_off == MN_rdmsr
          || t->mnem_off == MN_wrmsrns)
-       {
-         for (j = 0; j < i.imm_operands; j++)
-           i.types[j] = smallest_imm_type (i.op[j].imms->X_add_number);
-       }
+       i.types[0] = smallest_imm_type (i.op[0].imms->X_add_number);
       else
        optimize_imm ();
     }
@@ -8522,7 +8521,7 @@ optimize_imm (void)
               && current_templates.start->mnem_off != MN_jmpabs))
     guess_suffix = LONG_MNEM_SUFFIX;
 
-  for (op = i.operands; --op >= 0;)
+  for (op = i.imm_operands; --op >= 0;)
     if (operand_type_check (i.types[op], imm))
       {
        switch (i.op[op].imms->X_op)

diff --git a/gas/testsuite/gas/i386/x86-64-msr_imm-inval.l b/gas/testsuite/gas/i386/x86-64-msr_imm-inval.l
index 6825a145984dc086d75e4c5e8f3dbd684c8b84c2..bbafdb47844f96af7b7f60f6acc6dd2bfcf7ea5c 100644 (file)
--- a/gas/testsuite/gas/i386/x86-64-msr_imm-inval.l
+++ b/gas/testsuite/gas/i386/x86-64-msr_imm-inval.l
@@ -1,5 +1,7 @@
 .* Assembler messages:
 .*:5: Error: operand type mismatch for `rdmsr'
 .*:6: Error: operand type mismatch for `rdmsr'
-.*:7: Error: operand type mismatch for `wrmsrns'
+.*:7: Error: operand type mismatch for `rdmsr'
 .*:8: Error: operand type mismatch for `wrmsrns'
+.*:9: Error: operand type mismatch for `wrmsrns'
+.*:10: Error: operand type mismatch for `wrmsrns'

diff --git a/gas/testsuite/gas/i386/x86-64-msr_imm-inval.s b/gas/testsuite/gas/i386/x86-64-msr_imm-inval.s
index e12e5be392f95de26e1faf49424acc1e9967d8f0..6a245bcbcf696160a63fad6aade890929728bc5c 100644 (file)
--- a/gas/testsuite/gas/i386/x86-64-msr_imm-inval.s
+++ b/gas/testsuite/gas/i386/x86-64-msr_imm-inval.s
@@ -4,5 +4,7 @@
 _start:
        rdmsr  $5151515151515151, %r12
        rdmsr  $-515151, %r12
+       rdmsr  (%rax), $0
        wrmsrns  %r12, $5151515151515151
        wrmsrns  %r12, $-515151
+       wrmsrns  $0, (%rax)

diff --git a/gas/testsuite/gas/i386/x86-64-user_msr-inval.l b/gas/testsuite/gas/i386/x86-64-user_msr-inval.l
index 9eb3044e16eea818d26de3fd3cbfa143aa1491e1..59383063c89faed39920c247d22643c4c08dced7 100644 (file)
--- a/gas/testsuite/gas/i386/x86-64-user_msr-inval.l
+++ b/gas/testsuite/gas/i386/x86-64-user_msr-inval.l
@@ -3,7 +3,9 @@
 .*:6: Error: operand type mismatch for `urdmsr'
 .*:7: Error: operand type mismatch for `urdmsr'
 .*:8: Error: operand type mismatch for `urdmsr'
-.*:9: Error: operand type mismatch for `uwrmsr'
+.*:9: Error: operand type mismatch for `urdmsr'
 .*:10: Error: operand type mismatch for `uwrmsr'
 .*:11: Error: operand type mismatch for `uwrmsr'
 .*:12: Error: operand type mismatch for `uwrmsr'
+.*:13: Error: operand type mismatch for `uwrmsr'
+.*:14: Error: operand type mismatch for `uwrmsr'

diff --git a/gas/testsuite/gas/i386/x86-64-user_msr-inval.s b/gas/testsuite/gas/i386/x86-64-user_msr-inval.s
index e7b6d6eea83f5238adbe10e96a47311f7195d926..ac22391baa3c62810093ba7fedd18270999a2b19 100644 (file)
--- a/gas/testsuite/gas/i386/x86-64-user_msr-inval.s
+++ b/gas/testsuite/gas/i386/x86-64-user_msr-inval.s
@@ -6,7 +6,9 @@ _start:
        urdmsr  $-32767, %r14
        urdmsr  $-2147483648, %r14
        urdmsr  $0x7fffffffffffffff, %r14
+       urdmsr  (%rax), $0
        uwrmsr  %r12, $-1
        uwrmsr  %r12, $-32767
        uwrmsr  %r12, $-2147483648
        uwrmsr  %r12, $0x7fffffffffffffff
+       uwrmsr  $0, (%rax)