[x86 PATCH] PR target/110588: Add *bt_setncqi_2 to generate btl

[Roger Sayle]

This patch resolves PR target/110588 to catch another case in combine
where the i386 backend should be generating a btl instruction.  This adds
another define_insn_and_split to recognize the RTL representation for this
case.

I also noticed that two related define_insn_and_split weren't using the
preferred string style for single statement preparation-statements, so
I've reformatted these to be consistent in style with the new one.

This patch has been tested on x86_64-pc-linux-gnu with make bootstrap
and make -k check, both with and without --target_board=unix{-m32}
with no new failures.  Ok for mainline?


2023-07-13  Roger Sayle  <ro...@nextmovesoftware.com>

gcc/ChangeLog
        PR target/110588
        * config/i386/i386.md (*bt<mode>_setcqi): Prefer string form
        preparation statement over braces for a single statement.
        (*bt<mode>_setncqi): Likewise.
        (*bt<mode>_setncqi_2): New define_insn_and_split.

gcc/testsuite/ChangeLog
        PR target/110588
        * gcc.target/i386/pr110588.c: New test case.


Thanks again,
Roger
--


diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index e47ced1..04eca049 100644
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -16170,9 +16170,7 @@
          (const_int 0)))
    (set (match_dup 0)
         (eq:QI (reg:CCC FLAGS_REG) (const_int 0)))]
-{
-  operands[2] = lowpart_subreg (SImode, operands[2], QImode);
-})
+  "operands[2] = lowpart_subreg (SImode, operands[2], QImode);")
 
 ;; Help combine recognize bt followed by setnc
 (define_insn_and_split "*bt<mode>_setncqi"
@@ -16193,9 +16191,7 @@
          (const_int 0)))
    (set (match_dup 0)
         (ne:QI (reg:CCC FLAGS_REG) (const_int 0)))]
-{
-  operands[2] = lowpart_subreg (SImode, operands[2], QImode);
-})
+  "operands[2] = lowpart_subreg (SImode, operands[2], QImode);")
 
 (define_insn_and_split "*bt<mode>_setnc<mode>"
   [(set (match_operand:SWI48 0 "register_operand")
@@ -16219,6 +16215,27 @@
   operands[2] = lowpart_subreg (SImode, operands[2], QImode);
   operands[3] = gen_reg_rtx (QImode);
 })
+
+;; Help combine recognize bt followed by setnc (PR target/110588)
+(define_insn_and_split "*bt<mode>_setncqi_2"
+  [(set (match_operand:QI 0 "register_operand")
+       (eq:QI
+         (zero_extract:SWI48
+           (match_operand:SWI48 1 "register_operand")
+           (const_int 1)
+           (zero_extend:SI (match_operand:QI 2 "register_operand")))
+         (const_int 0)))
+   (clobber (reg:CC FLAGS_REG))]
+  "TARGET_USE_BT && ix86_pre_reload_split ()"
+  "#"
+  "&& 1"
+  [(set (reg:CCC FLAGS_REG)
+        (compare:CCC
+         (zero_extract:SWI48 (match_dup 1) (const_int 1) (match_dup 2))
+         (const_int 0)))
+   (set (match_dup 0)
+        (ne:QI (reg:CCC FLAGS_REG) (const_int 0)))]
+  "operands[2] = lowpart_subreg (SImode, operands[2], QImode);")
 
 ;; Store-flag instructions.
 
diff --git a/gcc/testsuite/gcc.target/i386/pr110588.c 
b/gcc/testsuite/gcc.target/i386/pr110588.c
new file mode 100644
index 0000000..4505c87
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr110588.c
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -mtune=core2" } */
+
+unsigned char foo (unsigned char x, int y)
+{
+  int _1 = (int) x;
+  int _2 = _1 >> y;
+  int _3 = _2 & 1;
+  unsigned char _8 = (unsigned char) _3;
+  unsigned char _6 = _8 ^ 1;
+  return _6;
+}
+
+/* { dg-final { scan-assembler "btl" } } */
+/* { dg-final { scan-assembler "setnc" } } */
+/* { dg-final { scan-assembler-not "sarl" } } */
+/* { dg-final { scan-assembler-not "andl" } } */
+/* { dg-final { scan-assembler-not "xorl" } } */