i386: Add define_insn_and_split patterns for btrl [PR96938]

In the following testcase we only optimize f2 and f7 to btrl, although we
should optimize that way all of the functions.  The problem is the type
demotion/narrowing (which is performed solely during the generic folding and
not later), without it we see the AND performed in SImode and match it as
btrl, but with it while the shifts are still performed in SImode, the
AND is already done in QImode or HImode low part of the shift.

2021-01-13  Jakub Jelinek  <jakub@redhat.com>

	PR target/96938
	* config/i386/i386.md (*btr<mode>_1, *btr<mode>_2): New
	define_insn_and_split patterns.
	(splitter after *btr<mode>_2): New splitter.

	* gcc.target/i386/pr96938.c: New test.

2 files changed, 131 insertions, 0 deletions

diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index c102312..b60784a 100644
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -12419,6 +12419,71 @@
 	     (match_dup 3)))
       (clobber (reg:CC FLAGS_REG))])])
 
+(define_insn_and_split "*btr<mode>_1"
+  [(set (match_operand:SWI12 0 "register_operand")
+	(and:SWI12
+	  (subreg:SWI12
+	    (rotate:SI (const_int -2)
+		       (match_operand:QI 2 "register_operand")) 0)
+	  (match_operand:SWI12 1 "nonimmediate_operand")))
+   (clobber (reg:CC FLAGS_REG))]
+  "TARGET_USE_BT && ix86_pre_reload_split ()"
+  "#"
+  "&& 1"
+  [(parallel
+     [(set (match_dup 0)
+	   (and:SI (rotate:SI (const_int -2) (match_dup 2))
+		   (match_dup 1)))
+      (clobber (reg:CC FLAGS_REG))])]
+{
+  operands[0] = lowpart_subreg (SImode, operands[0], <MODE>mode);
+  if (MEM_P (operands[1]))
+    operands[1] = force_reg (<MODE>mode, operands[1]);
+  operands[1] = lowpart_subreg (SImode, operands[1], <MODE>mode);
+})
+
+(define_insn_and_split "*btr<mode>_2"
+  [(set (zero_extract:HI
+	  (match_operand:SWI12 0 "nonimmediate_operand")
+	  (const_int 1)
+	  (zero_extend:SI (match_operand:QI 1 "register_operand")))
+	(const_int 0))
+   (clobber (reg:CC FLAGS_REG))]
+  "TARGET_USE_BT && ix86_pre_reload_split ()"
+  "#"
+  "&& MEM_P (operands[0])"
+  [(set (match_dup 2) (match_dup 0))
+   (parallel
+     [(set (match_dup 3)
+	   (and:SI (rotate:SI (const_int -2) (match_dup 1))
+		   (match_dup 4)))
+      (clobber (reg:CC FLAGS_REG))])
+   (set (match_dup 0) (match_dup 5))]
+{
+  operands[2] = gen_reg_rtx (<MODE>mode);
+  operands[5] = gen_reg_rtx (<MODE>mode);
+  operands[3] = lowpart_subreg (SImode, operands[5], <MODE>mode);
+  operands[4] = lowpart_subreg (SImode, operands[2], <MODE>mode);
+})
+
+(define_split
+  [(set (zero_extract:HI
+	  (match_operand:SWI12 0 "register_operand")
+	  (const_int 1)
+	  (zero_extend:SI (match_operand:QI 1 "register_operand")))
+	(const_int 0))
+   (clobber (reg:CC FLAGS_REG))]
+  "TARGET_USE_BT && ix86_pre_reload_split ()"
+  [(parallel
+     [(set (match_dup 0)
+	   (and:SI (rotate:SI (const_int -2) (match_dup 1))
+		   (match_dup 2)))
+      (clobber (reg:CC FLAGS_REG))])]
+{
+  operands[2] = lowpart_subreg (SImode, operands[0], <MODE>mode);
+  operands[0] = lowpart_subreg (SImode, operands[0], <MODE>mode);
+})
+
 ;; These instructions are never faster than the corresponding
 ;; and/ior/xor operations when using immediate operand, so with
 ;; 32-bit there's no point.  But in 64-bit, we can't hold the
diff --git a/gcc/testsuite/gcc.target/i386/pr96938.c b/gcc/testsuite/gcc.target/i386/pr96938.c
new file mode 100644
index 0000000..832cdd4
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr96938.c
@@ -0,0 +1,66 @@
+/* PR target/96938 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -masm=att" } */
+/* { dg-final { scan-assembler-times "\tbtrl\t" 10 } } */
+
+void
+f1 (unsigned char *f, int o, unsigned char v)
+{
+  *f = (*f & ~(1 << o)) | (v << o);
+}
+
+void
+f2 (unsigned char *f, int o, unsigned char v)
+{
+  int t = *f & ~(1 << o);
+  *f = t | (v << o);
+}
+
+void
+f3 (unsigned char *f, int o, unsigned char v)
+{
+  *f &= ~(1 << o);
+}
+
+void
+f4 (unsigned char *f, int o, unsigned char v)
+{
+  *f = (*f & ~(1 << (o & 31))) | v;
+}
+
+void
+f5 (unsigned char *f, int o, unsigned char v)
+{
+  *f = (*f & ~(1 << (o & 31))) | (v << (o & 31));
+}
+
+void
+f6 (unsigned short *f, int o, unsigned short v)
+{
+  *f = (*f & ~(1 << o)) | (v << o);
+}
+
+void
+f7 (unsigned short *f, int o, unsigned short v)
+{
+  int t = *f & ~(1 << o);
+  *f = t | (v << o);
+}
+
+void
+f8 (unsigned short *f, int o, unsigned short v)
+{
+  *f &= ~(1 << o);
+}
+
+void
+f9 (unsigned short *f, int o, unsigned short v)
+{
+  *f = (*f & ~(1 << (o & 31))) | v;
+}
+
+void
+f10 (unsigned short *f, int o, unsigned short v)
+{
+  *f = (*f & ~(1 << (o & 31))) | (v << (o & 31));
+}