[binutils-gdb] [AArch64][SVE 13/32] Add an F_STRICT flag

[Richard Sandiford <rsandifo at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=4989adac848eb8f2fee8b98d9615d2fded22623b

commit 4989adac848eb8f2fee8b98d9615d2fded22623b
Author: Richard Sandiford <richard.sandiford@arm.com>
Date:   Wed Sep 21 16:51:00 2016 +0100

    [AArch64][SVE 13/32] Add an F_STRICT flag
    
    SVE predicate operands can appear in three forms:
    
    1. unsuffixed: "Pn"
    2. with a predication type: "Pn/[ZM]"
    3. with a size suffix: "Pn.[BHSD]"
    
    No variation is allowed: unsuffixed operands cannot have a (redundant)
    suffix, and the suffixes can never be dropped.  Unsuffixed Pn are used
    in LDR and STR, but they are also used for Pg operands in cases where
    the result is scalar and where there is therefore no choice to be made
    between "merging" and "zeroing".  This means that some Pg operands have
    suffixes and others don't.
    
    It would be possible to use context-sensitive parsing to handle
    this difference.  The tc-aarch64.c code would then raise an error
    if the wrong kind of suffix is used for a particular instruction.
    
    However, we get much more user-friendly error messages if we parse
    all three forms for all SVE instructions and record the suffix as a
    qualifier.  The normal qualifier matching code can then report cases
    where the wrong kind of suffix is used.  This is a slight extension
    of existing usage, which really only checks for the wrong choice of
    suffix within a particular kind of suffix.
    
    The only catch is a that a "NIL" entry in the qualifier list
    specifically means "no suffix should be present" (case 1 above).
    NIL isn't a wildcard here.  It also means that an instruction that
    requires all-NIL qualifiers can fail to match (because a suffix was
    supplied when it shouldn't have been); this requires a slight change
    to find_best_match.
    
    This patch adds an F_STRICT flag to select this behaviour.
    The flag will be set for all SVE instructions.  The behaviour
    for other instructions doesn't change.
    
    include/
    	* opcode/aarch64.h (F_STRICT): New flag.
    
    opcodes/
    	* aarch64-opc.c (match_operands_qualifier): Handle F_STRICT.
    
    gas/
    	* config/tc-aarch64.c (find_best_match): Simplify, allowing an
    	instruction with all-NIL qualifiers to fail to match.

Diff:
---
 gas/ChangeLog            |  5 +++++
 gas/config/tc-aarch64.c  |  5 +----
 include/ChangeLog        |  4 ++++
 include/opcode/aarch64.h |  4 +++-
 opcodes/ChangeLog        |  4 ++++
 opcodes/aarch64-opc.c    | 11 ++++++++++-
 6 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/gas/ChangeLog b/gas/ChangeLog
index d7df100..ac9d359 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,5 +1,10 @@
 2016-09-21  Richard Sandiford  <richard.sandiford@arm.com>
 
+	* config/tc-aarch64.c (find_best_match): Simplify, allowing an
+	instruction with all-NIL qualifiers to fail to match.
+
+2016-09-21  Richard Sandiford  <richard.sandiford@arm.com>
+
 	* config/tc-aarch64.c (parse_address_main): Remove reloc and
 	accept_reg_post_index parameters.  Parse relocations and register
 	post indexes unconditionally.
diff --git a/gas/config/tc-aarch64.c b/gas/config/tc-aarch64.c
index f82fdb9..f50de70 100644
--- a/gas/config/tc-aarch64.c
+++ b/gas/config/tc-aarch64.c
@@ -4134,7 +4134,7 @@ find_best_match (const aarch64_inst *instr,
     }
 
   max_num_matched = 0;
-  idx = -1;
+  idx = 0;
 
   /* For each pattern.  */
   for (i = 0; i < AARCH64_MAX_QLF_SEQ_NUM; ++i, ++qualifiers_list)
@@ -4146,9 +4146,6 @@ find_best_match (const aarch64_inst *instr,
       if (empty_qualifier_sequence_p (qualifiers) == TRUE)
 	{
 	  DEBUG_TRACE_IF (i == 0, "empty list of qualifier sequence");
-	  if (i != 0 && idx == -1)
-	    /* If nothing has been matched, return the 1st sequence.  */
-	    idx = 0;
 	  break;
 	}
 
diff --git a/include/ChangeLog b/include/ChangeLog
index 2c922c4..21ddbfd 100644
--- a/include/ChangeLog
+++ b/include/ChangeLog
@@ -1,3 +1,7 @@
+2016-09-21  Richard Sandiford  <richard.sandiford@arm.com>
+
+	* opcode/aarch64.h (F_STRICT): New flag.
+
 2016-09-07  Richard Earnshaw  <rearnsha@arm.com>
 
 	* opcode/arm.h (ARM_ARCH_V8A_CRC): New architecture.
diff --git a/include/opcode/aarch64.h b/include/opcode/aarch64.h
index 1e38749..24a2ddb 100644
--- a/include/opcode/aarch64.h
+++ b/include/opcode/aarch64.h
@@ -598,7 +598,9 @@ extern aarch64_opcode aarch64_opcode_table[];
 #define F_OD(X) (((X) & 0x7) << 24)
 /* Instruction has the field of 'sz'.  */
 #define F_LSE_SZ (1 << 27)
-/* Next bit is 28.  */
+/* Require an exact qualifier match, even for NIL qualifiers.  */
+#define F_STRICT (1ULL << 28)
+/* Next bit is 29.  */
 
 static inline bfd_boolean
 alias_opcode_p (const aarch64_opcode *opcode)
diff --git a/opcodes/ChangeLog b/opcodes/ChangeLog
index b47f034..c12ea3a 100644
--- a/opcodes/ChangeLog
+++ b/opcodes/ChangeLog
@@ -1,5 +1,9 @@
 2016-09-21  Richard Sandiford  <richard.sandiford@arm.com>
 
+	* aarch64-opc.c (match_operands_qualifier): Handle F_STRICT.
+
+2016-09-21  Richard Sandiford  <richard.sandiford@arm.com>
+
 	* aarch64-gen.c (indented_print): Avoid hard-coded indentation limit.
 
 2016-09-15  Claudiu Zissulescu  <claziss@synopsys.com>
diff --git a/opcodes/aarch64-opc.c b/opcodes/aarch64-opc.c
index 322b991..d870fd6 100644
--- a/opcodes/aarch64-opc.c
+++ b/opcodes/aarch64-opc.c
@@ -854,7 +854,7 @@ aarch64_find_best_match (const aarch64_inst *inst,
 static int
 match_operands_qualifier (aarch64_inst *inst, bfd_boolean update_p)
 {
-  int i;
+  int i, nops;
   aarch64_opnd_qualifier_seq_t qualifiers;
 
   if (!aarch64_find_best_match (inst, inst->opcode->qualifiers_list, -1,
@@ -864,6 +864,15 @@ match_operands_qualifier (aarch64_inst *inst, bfd_boolean update_p)
       return 0;
     }
 
+  if (inst->opcode->flags & F_STRICT)
+    {
+      /* Require an exact qualifier match, even for NIL qualifiers.  */
+      nops = aarch64_num_of_operands (inst->opcode);
+      for (i = 0; i < nops; ++i)
+	if (inst->operands[i].qualifier != qualifiers[i])
+	  return FALSE;
+    }
+
   /* Update the qualifiers.  */
   if (update_p == TRUE)
     for (i = 0; i < AARCH64_MAX_OPND_NUM; ++i)