The popcount expansion uses SIMD instructions acting on 64-bit values.
As a result a popcount of a 32-bit integer requires zero-extension before
moving the zero-extended value into an FP register. This patch adds
support for zero-extended int->FP moves to avoid the redundant uxtw.
Similarly, add support for a 32-bit zero-extending load->FP register.
Add a missing 'fp' arch attribute to the related 8/16-bit pattern.
int f (int a)
{
return __builtin_popcount (a);
}
Before:
uxtw x0, w0
fmov d0, x0
cnt v0.8b, v0.8b
addv b0, v0.8b
fmov w0, s0
ret
After:
fmov s0, w0
cnt v0.8b, v0.8b
addv b0, v0.8b
fmov w0, s0
ret
Passes regress on AArch64, OK for commit?
ChangeLog:
2018-09-27 Wilco Dijkstra <wdijk...@arm.com>
gcc/
* config/aarch64/aarch64.md (zero_extendsidi2_aarch64): Add w=r and
w=m zeroextend alternatives.
(zero_extend<SHORT:mode><GPI:mode>2_aarch64): Add arch attribute.
testsuite/
* gcc.target/aarch64/popcnt.c: Test zero-extended popcount.
---
diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
index
ef2368706e88a551b9d0d2db2385860112bdbdde..c0b39ea876f76b54b31088d8d63d96a9cbcf8b88
100644
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -1588,13 +1588,16 @@
)
(define_insn "*zero_extendsidi2_aarch64"
- [(set (match_operand:DI 0 "register_operand" "=r,r")
- (zero_extend:DI (match_operand:SI 1 "nonimmediate_operand" "r,m")))]
+ [(set (match_operand:DI 0 "register_operand" "=r,r,w,w")
+ (zero_extend:DI (match_operand:SI 1 "nonimmediate_operand"
"r,m,r,m")))]
""
"@
uxtw\t%0, %w1
- ldr\t%w0, %1"
- [(set_attr "type" "extend,load_4")]
+ ldr\t%w0, %1
+ fmov\t%s0, %w1
+ ldr\t%s0, %1"
+ [(set_attr "type" "extend,load_4,fmov,f_loads")
+ (set_attr "arch" "*,*,fp,fp")]
)
(define_insn "*load_pair_zero_extendsidi2_aarch64"
@@ -1634,7 +1637,8 @@
and\t%<GPI:w>0, %<GPI:w>1, <SHORT:short_mask>
ldr<SHORT:size>\t%w0, %1
ldr\t%<SHORT:size>0, %1"
- [(set_attr "type" "logic_imm,load_4,load_4")]
+ [(set_attr "type" "logic_imm,load_4,f_loads")
+ (set_attr "arch" "*,*,fp")]
)
(define_expand "<optab>qihi2"
diff --git a/gcc/testsuite/gcc.target/aarch64/popcnt.c
b/gcc/testsuite/gcc.target/aarch64/popcnt.c
index
7e957966d8e81b8633a444bb42944d0da82ae5db..8fb8db82e052bd898aa8513710fd94f892d80b61
100644
--- a/gcc/testsuite/gcc.target/aarch64/popcnt.c
+++ b/gcc/testsuite/gcc.target/aarch64/popcnt.c
@@ -19,5 +19,14 @@ foo2 (long long x)
return __builtin_popcountll (x);
}
-/* { dg-final { scan-assembler-not "popcount" } } */
-/* { dg-final { scan-assembler-times "cnt\t" 3 } } */
+int
+foo3 (int *p)
+{
+ return __builtin_popcount (*p);
+}
+
+/* { dg-final { scan-assembler-not {popcount} } } */
+/* { dg-final { scan-assembler-times {cnt\t} 4 } } */
+/* { dg-final { scan-assembler-times {fmov\ts} 1 } } */
+/* { dg-final { scan-assembler-times {fmov\td} 2 } } */
+/* { dg-final { scan-assembler-times {ldr\ts} 1 } } */
