[patch,avr] PR114975: Better 8-bit popcount detection.

[patch,avr] PR114975: Better 8-bit popcount detection.

[Georg-Johann Lay]

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Add a pattern for better popcount detection.

Ok for master?

Johann

--

AVR: target/114975 - Add combine-pattern for __popcountqi2.

	PR target/114975
gcc/
	* config/avr/avr.md: Add combine pattern for
	8-bit popcount detection.

gcc/testsuite/
	* gcc.target/avr/pr114975-popcount.c: New test.

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diff --git a/gcc/config/avr/avr.md b/gcc/config/avr/avr.md
index 97f42be7729..d4fcff46123 100644
--- a/gcc/config/avr/avr.md
+++ b/gcc/config/avr/avr.md
@@ -8527,6 +8542,19 @@ (define_expand "popcountsi2"
     operands[2] = gen_reg_rtx (HImode);
   })
 
+(define_insn_and_split "*popcounthi2.split8"
+  [(set (reg:HI 24)
+        (zero_extend:HI (popcount:QI (match_operand:QI 0 "register_operand"))))]
+  "! reload_completed"
+  { gcc_unreachable(); }
+  "&& 1"
+  [(set (reg:QI 24)
+        (match_dup 0))
+   (set (reg:QI 24)
+        (popcount:QI (reg:QI 24)))
+   (set (reg:QI 25)
+        (const_int 0))])
+
 (define_insn_and_split "*popcounthi2.libgcc_split"
   [(set (reg:HI 24)
         (popcount:HI (reg:HI 24)))]
diff --git a/gcc/testsuite/gcc.target/avr/pr114975-popcount.c b/gcc/testsuite/gcc.target/avr/pr114975-popcount.c
new file mode 100644
index 00000000000..87eb56b56c5
--- /dev/null
+++ b/gcc/testsuite/gcc.target/avr/pr114975-popcount.c
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-Os" } */
+
+typedef __UINT8_TYPE__ uint8_t;
+
+uint8_t use_pop1 (int y, uint8_t x)
+{
+    return 1 + __builtin_popcount (x);
+}
+
+uint8_t use_pop2 (uint8_t x)
+{
+	x += 1;
+    return 1 - __builtin_popcount (x);
+}
+
+/* { dg-final { scan-assembler-times "__popcountqi2" 2 } } */

Re: [patch,avr] PR114975: Better 8-bit popcount detection.

[Jeff Law]

On 5/7/24 11:25 AM, Georg-Johann Lay wrote:
> Add a pattern for better popcount detection.
> 
> Ok for master?
> 
> Johann
> 
> -- 
> 
> AVR: target/114975 - Add combine-pattern for __popcountqi2.
> 
>      PR target/114975
> gcc/
>      * config/avr/avr.md: Add combine pattern for
>      8-bit popcount detection.
> 
> gcc/testsuite/
>      * gcc.target/avr/pr114975-popcount.c: New test.
OK
jeff