Sorry for the delay, but here's the third and final version.
This includes the requested cpp symbol and updated documentation.
r~
* config/i386/constraints.md (Bf): New constraint.
* config/i386/i386-c.c (ix86_target_macros): Define
__GCC_ASM_FLAG_OUTPUTS__.
* config/i386/i386.c (ix86_md_asm_adjust): Handle =@cc* constraints
as flags outputs.
* doc/extend.texi (FlagOutputOperands): Document them.
* gcc.target/i386/asm-flag-1.c: New.
* gcc.target/i386/asm-flag-2.c: New.
* gcc.target/i386/asm-flag-3.c: New.
* gcc.target/i386/asm-flag-4.c: New.
* gcc.target/i386/asm-flag-5.c: New.
diff --git a/gcc/config/i386/constraints.md b/gcc/config/i386/constraints.md
index c718bc1..2861d8d 100644
--- a/gcc/config/i386/constraints.md
+++ b/gcc/config/i386/constraints.md
@@ -146,11 +146,16 @@
@internal Lower SSE register when avoiding REX prefix and all SSE registers
otherwise.)
;; We use the B prefix to denote any number of internal operands:
+;; f FLAGS_REG
;; g GOT memory operand.
;; s Sibcall memory operand, not valid for TARGET_X32
;; w Call memory operand, not valid for TARGET_X32
;; z Constant call address operand.
+(define_constraint Bf
+ @internal Flags register operand.
+ (match_operand 0 flags_reg_operand))
+
(define_constraint Bg
@internal GOT memory operand.
(match_operand 0 GOT_memory_operand))
diff --git a/gcc/config/i386/i386-c.c b/gcc/config/i386/i386-c.c
index 28444f9..d506345 100644
--- a/gcc/config/i386/i386-c.c
+++ b/gcc/config/i386/i386-c.c
@@ -560,6 +560,8 @@ ix86_target_macros (void)
cpp_define_formatted (parse_in, __ATOMIC_HLE_ACQUIRE=%d, IX86_HLE_ACQUIRE);
cpp_define_formatted (parse_in, __ATOMIC_HLE_RELEASE=%d, IX86_HLE_RELEASE);
+ cpp_define (parse_in, __GCC_ASM_FLAG_OUTPUTS__);
+
ix86_target_macros_internal (ix86_isa_flags,
ix86_arch,
ix86_tune,
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 9598600..144c1a6 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -4,21 +4,144 @@ ix86_c_mode_for_suffix (char suffix)
/* Worker function for TARGET_MD_ASM_ADJUST.
- We do this in the new i386 backend to maintain source compatibility
+ We implement asm flag outputs, and maintain source compatibility
with the old cc0-based compiler. */
static rtx_insn *
-ix86_md_asm_adjust (vecrtx /*outputs*/, vecrtx /*inputs*/,
- vecconst char * /*constraints*/,
+ix86_md_asm_adjust (vecrtx outputs, vecrtx /*inputs*/,
+ vecconst char * constraints,
vecrtx clobbers, HARD_REG_SET clobbered_regs)
{
- clobbers.safe_push (gen_rtx_REG (CCmode, FLAGS_REG));
clobbers.safe_push (gen_rtx_REG (CCFPmode, FPSR_REG));
-
- SET_HARD_REG_BIT (clobbered_regs, FLAGS_REG);
SET_HARD_REG_BIT (clobbered_regs, FPSR_REG);
- return NULL;
+ bool saw_asm_flag = false;
+
+ start_sequence ();
+ for (unsigned i = 0, n = outputs.length (); i n; ++i)
+{
+ const char *con = constraints[i];
+ if (strncmp (con, =@cc, 4) != 0)
+ continue;
+ con += 4;
+ if (strchr (con, ',') != NULL)
+ {
+ error (alternatives not allowed in asm flag output);
+ continue;
+ }
+
+ bool invert = false;
+ if (con[0] == 'n')
+ invert = true, con++;
+
+ machine_mode mode = CCmode;
+ rtx_code code = UNKNOWN;
+
+ switch (con[0])
+ {
+ case 'a':
+ if (con[1] == 0)
+ mode = CCAmode, code = EQ;
+ else if (con[1] == 'e' con[2] == 0)
+ mode = CCCmode, code = EQ;
+ break;
+ case 'b':
+ if (con[1] == 0)
+ mode = CCCmode, code = EQ;
+ else if (con[1] == 'e' con[2] == 0)
+ mode = CCAmode, code = NE;
+ break;
+ case 'c':
+ if (con[1] == 0)
+ mode = CCCmode, code = EQ;
+ break;
+ case 'e':
+ if (con[1] == 0)
+ mode = CCZmode, code = EQ;
+ break;
+ case 'g':
+ if (con[1] == 0)
+ mode = CCGCmode, code = GT;
+ else if (con[1] == 'e' con[2] == 0)
+ mode = CCGCmode, code = GE;
+ break;
+ case 'l':
+ if (con[1] == 0)
+ mode = CCGCmode, code = LT;
+ else if (con[1] == 'e' con[2] == 0)
+ mode = CCGCmode, code = LE;
+ break;
+ case 'o':
+ if (con[1] == 0)
+ mode = CCOmode, code = EQ;
+ break;
+ case 'p':
+ if (con[1] == 0)
+ mode = CCPmode, code = EQ;
+ break;
+ case 's':
+ if (con[1] == 0)
+ mode = CCSmode, code = EQ;
+ break;
+ case 'z':
+ if (con[1] == 0)
+ mode = CCZmode, code = EQ;
+ break;
+ }
+ if (code == UNKNOWN)
+ {
+ error (unknown asm flag output %qs,
