[gcc r12-7751] Extend splitter pattern to reversed condition by swapping then and else rtx. [PR target/104982]

[gcc r12-7751] Extend splitter pattern to reversed condition by swapping then and else rtx. [PR target/104982]

[hongtao Liu]

https://gcc.gnu.org/g:919fbffef0755562cd3b686c838069c20bc7878f

commit r12-7751-g919fbffef0755562cd3b686c838069c20bc7878f
Author: liuhongt <hongtao.liu@intel.com>
Date:   Mon Mar 21 20:54:30 2022 +0800

    Extend splitter pattern to reversed condition by swapping then and else rtx. [PR target/104982]
    
    Failed to match this instruction:
    (set (reg/v:SI 88 [ z ])
        (if_then_else:SI (eq (zero_extract:SI (reg:SI 92)
                    (const_int 1 [0x1])
                    (zero_extend:SI (subreg:QI (reg:SI 93) 0)))
                (const_int 0 [0]))
            (reg:SI 95)
            (reg:SI 94)))
    
    but it's equal to
    
    (set (reg/v:SI 88 [ z ])
        (if_then_else:SI (ne (zero_extract:SI (reg:SI 92)
                    (const_int 1 [0x1])
                    (zero_extend:SI (subreg:QI (reg:SI 93) 0)))
                (const_int 0 [0]))
            (reg:SI 94)
            (reg:SI 95)))
    
    which is the exact existing splitter.
    
    The patch will fix below regressions:
    
    On x86-64, r12-7687 caused:
    
    FAIL: gcc.target/i386/bt-5.c scan-assembler-not sar[lq][ \t]
    FAIL: gcc.target/i386/bt-5.c scan-assembler-times bt[lq][ \t] 7
    
    gcc/ChangeLog:
    
            PR target/104982
            * config/i386/i386.md (*jcc_bt<mode>_mask): Extend the
            following splitter to reversed condition.

Diff:
---
 gcc/config/i386/i386.md | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index 02f298c2846..c74edd1aaef 100644
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -14182,12 +14182,12 @@
 (define_split
   [(set (match_operand:SWI248 0 "register_operand")
 	(if_then_else:SWI248
-	 (ne
-	  (zero_extract:SWI48
-	   (match_operand:SWI48 1 "register_operand")
-	   (const_int 1)
-	   (zero_extend:SI (match_operand:QI 2 "register_operand")))
-	  (const_int 0))
+	 (match_operator 5 "bt_comparison_operator"
+	  [(zero_extract:SWI48
+	    (match_operand:SWI48 1 "register_operand")
+	    (const_int 1)
+	    (zero_extend:SI (match_operand:QI 2 "register_operand")))
+	   (const_int 0)])
 	 (match_operand:SWI248 3 "nonimmediate_operand")
 	 (match_operand:SWI248 4 "nonimmediate_operand")))]
   "TARGET_USE_BT && TARGET_CMOVE
@@ -14202,6 +14202,8 @@
 			     (match_dup 3)
 			     (match_dup 4)))]
 {
+  if (GET_CODE (operands[5]) == EQ)
+    std::swap (operands[3], operands[4]);
   operands[2] = lowpart_subreg (SImode, operands[2], QImode);
 })