x86: handle immediate operands for .insn

Since we have no insn suffix and it's also not realistic to infer
immediate size from the size of other (typically register) operands
(like optimize_imm() does), and since we also don't have a template
telling us permitted size(s), a new syntax construct is introduced to
allow size (and signedness) specification. In the absence of such, the
size is inferred from significant bits (which obviously may yield
inconsistent results at least for effectively negative values, depending
on whether BFD64 is enabled), and only if supplied expressions can be
evaluated at parsing time. Being explicit is generally recommended to
users.

Size specification is permitted at bit granularity, but of course the
eventually emitted immediate values will be padded up to 8-, 16-, 32-,
or 64-bit fields.

2 files changed, 108 insertions, 3 deletions

diff --git a/gas/config/tc-i386-intel.c b/gas/config/tc-i386-intel.c
index 98262bd..5a2bf6d 100644
--- a/gas/config/tc-i386-intel.c
+++ b/gas/config/tc-i386-intel.c
@@ -965,7 +965,8 @@ i386_intel_operand (char *operand_string, int got_a_float)
       i386_operand_type temp;
 
       /* Register operand.  */
-      if (intel_state.base || intel_state.index || intel_state.seg)
+      if (intel_state.base || intel_state.index || intel_state.seg
+          || i.imm_bits[this_operand])
 	{
 	  as_bad (_("invalid operand"));
 	  return 0;
@@ -998,6 +999,12 @@ i386_intel_operand (char *operand_string, int got_a_float)
 	   || intel_state.is_mem)
     {
       /* Memory operand.  */
+      if (i.imm_bits[this_operand])
+	{
+	  as_bad (_("invalid operand"));
+	  return 0;
+	}
+
       if (i.mem_operands)
 	{
 	  /* Handle
diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c
index c8e68d5..ea2ed0d 100644
--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -288,6 +288,7 @@ struct _i386_insn
     unsigned int flags[MAX_OPERANDS];
 #define Operand_PCrel 1
 #define Operand_Mem   2
+#define Operand_Signed 4 /* .insn only */
 
     /* Relocation type for operand */
     enum bfd_reloc_code_real reloc[MAX_OPERANDS];
@@ -310,6 +311,9 @@ struct _i386_insn
     /* .insn allows for reserved opcode spaces.  */
     unsigned char insn_opcode_space;
 
+    /* .insn also allows (requires) specifying immediate size.  */
+    unsigned char imm_bits[MAX_OPERANDS];
+
     /* Register is in low 3 bits of opcode.  */
     bool short_form;
 
@@ -5923,6 +5927,10 @@ swap_2_operands (unsigned int xchg1, unsigned int xchg2)
   i.reloc[xchg2] = i.reloc[xchg1];
   i.reloc[xchg1] = temp_reloc;
 
+  temp_flags = i.imm_bits[xchg2];
+  i.imm_bits[xchg2] = i.imm_bits[xchg1];
+  i.imm_bits[xchg1] = temp_flags;
+
   if (i.mask.reg)
     {
       if (i.mask.operand == xchg1)
@@ -10188,7 +10196,8 @@ output_imm (fragS *insn_start_frag, offsetT insn_start_off)
 
 	      if (i.types[n].bitfield.imm32s
 		  && (i.suffix == QWORD_MNEM_SUFFIX
-		      || (!i.suffix && i.tm.opcode_modifier.no_lsuf)))
+		      || (!i.suffix && i.tm.opcode_modifier.no_lsuf)
+		      || dot_insn ()))
 		sign = 1;
 	      else
 		sign = 0;
@@ -11216,6 +11225,57 @@ s_insn (int dummy ATTRIBUTE_UNUSED)
       if (i.disp_operands && !optimize_disp (&i.tm))
 	goto done;
 
+      /* Establish size for immediate operands.  */
+      for (j = 0; j < i.imm_operands; ++j)
+	{
+	  expressionS *expP = i.op[j].imms;
+
+	  gas_assert (operand_type_check (i.types[j], imm));
+	  operand_type_set (&i.types[j], 0);
+
+	  if (i.imm_bits[j] > 32)
+	    i.types[j].bitfield.imm64 = 1;
+	  else if (i.imm_bits[j] > 16)
+	    {
+	      if (flag_code == CODE_64BIT && (i.flags[j] & Operand_Signed))
+		i.types[j].bitfield.imm32s = 1;
+	      else
+		i.types[j].bitfield.imm32 = 1;
+	    }
+	  else if (i.imm_bits[j] > 8)
+	    i.types[j].bitfield.imm16 = 1;
+	  else if (i.imm_bits[j] > 0)
+	    {
+	      if (i.flags[j] & Operand_Signed)
+		i.types[j].bitfield.imm8s = 1;
+	      else
+		i.types[j].bitfield.imm8 = 1;
+	    }
+	  else if (expP->X_op == O_constant)
+	    {
+	      i.types[j] = smallest_imm_type (expP->X_add_number);
+	      i.types[j].bitfield.imm1 = 0;
+	      /* Oddly enough imm_size() checks imm64 first, so the bit needs
+		 zapping since smallest_imm_type() sets it unconditionally.  */
+	      if (flag_code != CODE_64BIT)
+		{
+		  i.types[j].bitfield.imm64 = 0;
+		  i.types[j].bitfield.imm32s = 0;
+		  i.types[j].bitfield.imm32 = 1;
+		}
+	      else if (i.types[j].bitfield.imm32 || i.types[j].bitfield.imm32s)
+		i.types[j].bitfield.imm64 = 0;
+	    }
+	  else
+	    /* Non-constant expressions are sized heuristically.  */
+	    switch (flag_code)
+	      {
+	      case CODE_64BIT: i.types[j].bitfield.imm32s = 1; break;
+	      case CODE_32BIT: i.types[j].bitfield.imm32 = 1; break;
+	      case CODE_16BIT: i.types[j].bitfield.imm16 = 1; break;
+	      }
+	}
+
       for (j = 0; j < i.operands; ++j)
 	i.tm.operand_types[j] = i.types[j];
 
@@ -11396,10 +11456,11 @@ check_VecOperations (char *op_string)
 	  else if (dot_insn () && *op_string == ':')
 	    {
 	    dot_insn_modifier:
-	      if (op_string[1] == 'd')
+	      switch (op_string[1])
 		{
 		  unsigned long n;
 
+		case 'd':
 		  if (i.memshift < 32)
 		    goto duplicated_vec_op;
 
@@ -11409,6 +11470,27 @@ check_VecOperations (char *op_string)
 		      ++i.memshift;
 		  if (i.memshift < 32 && n == 1)
 		    op_string = end_op;
+		  break;
+
+		case 's': case 'u':
+		  /* This isn't really a "vector" operation, but a sign/size
+		     specifier for immediate operands of .insn.  Note that AT&T
+		     syntax handles the same in i386_immediate().  */
+		  if (!intel_syntax)
+		    break;
+
+		  if (i.imm_bits[this_operand])
+		    goto duplicated_vec_op;
+
+		  n = strtoul (op_string + 2, &end_op, 0);
+		  if (n && n <= (flag_code == CODE_64BIT ? 64 : 32))
+		    {
+		      i.imm_bits[this_operand] = n;
+		      if (op_string[1] == 's')
+			i.flags[this_operand] |= Operand_Signed;
+		      op_string = end_op;
+		    }
+		  break;
 		}
 	    }
 	  /* Check masking operation.  */
@@ -11547,6 +11629,22 @@ i386_immediate (char *imm_start)
 
   exp_seg = expression (exp);
 
+  /* For .insn immediates there may be a size specifier.  */
+  if (dot_insn () && *input_line_pointer == '{' && input_line_pointer[1] == ':'
+      && (input_line_pointer[2] == 's' || input_line_pointer[2] == 'u'))
+    {
+      char *e;
+      unsigned long n = strtoul (input_line_pointer + 3, &e, 0);
+
+      if (*e == '}' && n && n <= (flag_code == CODE_64BIT ? 64 : 32))
+	{
+	  i.imm_bits[this_operand] = n;
+	  if (input_line_pointer[2] == 's')
+	    i.flags[this_operand] |= Operand_Signed;
+	  input_line_pointer = e + 1;
+	}
+    }
+
   SKIP_WHITESPACE ();
   if (*input_line_pointer)
     as_bad (_("junk `%s' after expression"), input_line_pointer);