[PATCH v4] LoongArch: Fixed a compilation failure with '%c' in inline assembly [PR107731].

[Lulu Cheng <chenglulu@loongson.cn>]

Co-authored-by: Yang Yujie <yangyujie@loongson.cn>

gcc/ChangeLog:

	* config/loongarch/loongarch.cc (loongarch_classify_address):
	Add precessint for CONST_INT.
	(loongarch_print_operand_reloc): Operand modifier 'c' is supported.
	(loongarch_print_operand): Increase the processing of '%c'.
	* doc/extend.texi: Adds documents for LoongArch operand modifiers.

gcc/testsuite/ChangeLog:

	* gcc.target/loongarch/tst-asm-const.c: Moved to...
	* gcc.target/loongarch/pr107731.c: ...here.

---
V2 -> v3:
1. Correct a clerical error.
2. Adding document for loongarch operand modifiers.

v3 -> v4:
Copy the description of "%c" "%n" "%a" "%l" from gccint.pdf to gcc.pdf.


---
 gcc/config/loongarch/loongarch.cc             | 14 ++++++++
 gcc/doc/extend.texi                           | 33 +++++++++++++++++++
 .../loongarch/{tst-asm-const.c => pr107731.c} |  6 ++--
 3 files changed, 50 insertions(+), 3 deletions(-)
 rename gcc/testsuite/gcc.target/loongarch/{tst-asm-const.c => pr107731.c} (78%)

diff --git a/gcc/config/loongarch/loongarch.cc b/gcc/config/loongarch/loongarch.cc
index c6b03fcf2f9..cdf190b985e 100644
--- a/gcc/config/loongarch/loongarch.cc
+++ b/gcc/config/loongarch/loongarch.cc
@@ -2075,6 +2075,11 @@ loongarch_classify_address (struct loongarch_address_info *info, rtx x,
       return (loongarch_valid_base_register_p (info->reg, mode, strict_p)
 	      && loongarch_valid_lo_sum_p (info->symbol_type, mode,
 					   info->offset));
+    case CONST_INT:
+      /* Small-integer addresses don't occur very often, but they
+	 are legitimate if $r0 is a valid base register.  */
+      info->type = ADDRESS_CONST_INT;
+      return IMM12_OPERAND (INTVAL (x));
 
     default:
       return false;
@@ -4933,6 +4938,7 @@ loongarch_print_operand_reloc (FILE *file, rtx op, bool hi64_part,
 
    'A'	Print a _DB suffix if the memory model requires a release.
    'b'	Print the address of a memory operand, without offset.
+   'c'  Print an integer.
    'C'	Print the integer branch condition for comparison OP.
    'd'	Print CONST_INT OP in decimal.
    'F'	Print the FPU branch condition for comparison OP.
@@ -4979,6 +4985,14 @@ loongarch_print_operand (FILE *file, rtx op, int letter)
        fputs ("_db", file);
       break;
 
+    case 'c':
+      if (CONST_INT_P (op))
+	fprintf (file, HOST_WIDE_INT_PRINT_DEC, INTVAL (op));
+      else
+	output_operand_lossage ("unsupported operand for code '%c'", letter);
+
+      break;
+
     case 'C':
       loongarch_print_int_branch_condition (file, code, letter);
       break;
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index adba057c190..1bb960266ed 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -10234,6 +10234,24 @@ generates multiple assembler instructions.
 Outputs @samp{@{}, @samp{|}, and @samp{@}} characters (respectively)
 into the assembler code.  When unescaped, these characters have special
 meaning to indicate multiple assembler dialects, as described below.
+
+@item %c@var{digit}
+It can be used to substitute an operand that is a constant value without
+the syntax that normally indicates an immediate operand.
+
+@item %n@var{digit}
+It's like @samp{%c@var{digit}} except that the value of the constant is
+negated before printing.
+
+@item %a@var{digit}
+It Can be used to substitute an operand as if it were a memory reference,
+with the actual operand treated as the address.  This may be useful when
+outputting a ``load address'' instruction, because often the assembler
+syntax for such an instruction requires you to write the operand as if it
+were a memory reference.
+
+@item %l@var{digit}
+It's used to substitute a @code{label_ref} into a jump instruction.
 @end table
 
 @subsubheading Multiple assembler dialects in @code{asm} templates
@@ -11374,6 +11392,21 @@ constant.  Used to select the specified bit position.
 @item @code{x} @tab Equivialent to @code{X}, but only for pointers.
 @end multitable
 
+@anchor{loongarchOperandmodifiers}
+@subsubsection LoongArch Operand Modifiers
+
+The list below describes the supported modifiers and their effects for LoongArch.
+
+@multitable @columnfractions .10 .90
+@headitem Modifier @tab Description
+@item @code{d} @tab Same as @code{c}.
+@item @code{i} @tab Print the character ''@code{i}'' if the operand is not a register.
+@item @code{m} @tab Same as @code{c}, but the printed value is @code{operand - 1}.
+@item @code{X} @tab Print a constant integer operand in hexadecimal.
+@item @code{z} @tab Print the operand in its unmodified form, followed by a comma.
+@end multitable
+
+
 @lowersections
 @include md.texi
 @raisesections
diff --git a/gcc/testsuite/gcc.target/loongarch/tst-asm-const.c b/gcc/testsuite/gcc.target/loongarch/pr107731.c
similarity index 78%
rename from gcc/testsuite/gcc.target/loongarch/tst-asm-const.c
rename to gcc/testsuite/gcc.target/loongarch/pr107731.c
index 2e04b99e301..80d84c48c6e 100644
--- a/gcc/testsuite/gcc.target/loongarch/tst-asm-const.c
+++ b/gcc/testsuite/gcc.target/loongarch/pr107731.c
@@ -1,13 +1,13 @@
-/* Test asm const. */
 /* { dg-do compile } */
 /* { dg-final { scan-assembler-times "foo:.*\\.long 1061109567.*\\.long 52" 1 } } */
+
 int foo ()
 {
   __asm__ volatile (
           "foo:"
           "\n\t"
-	  ".long %a0\n\t"
-	  ".long %a1\n\t"
+	  ".long %c0\n\t"
+	  ".long %c1\n\t"
 	  :
 	  :"i"(0x3f3f3f3f), "i"(52)
 	  :
-- 
2.31.1