This is a fix for PR125716, where under specific circumstances we end
up emitting an insn like:
(insn 32 26 27 2 (set (reg:V2HI 63 v31 [orig:130 _13 ] [130])
(reg:V2HI 0 x0 [orig:115 _13 ] [115])) "testcase.c":3:17 1392
{*aarch64_simd_movv2hi}
(nil))
for which aarch64_simd_mov instruction variant taking sub-64-bit vector
operands there is no (w,r) alternative and things blow up later during
reload.
This happens specifically in the case of reg-reg transfers and only
when transfer cost between relevant register classes is 2, which, as I've
learned thanks to Andrea's writeup at [0] (and as is confirmed by e.g.
gcc/lra-constraints.cc:4245), is a magic value that tells LRA/reload to not
try different reloads which would have helped here.
The testcase added is a blend between those provided in PR125716 and in
PR125947. As stable as affected tuning models may be, I've opted to
create a dedicated JSON file for this test to guarantee a GP2FP cost of 2.
Bootstrapped and regtested on aarch64-linux-gnu with and without
-mtune=octeontx81.
[0] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125947#c1
PR target/125716
gcc/ChangeLog:
* config/aarch64/aarch64-simd.md (*aarch64_simd_mov<mode>): Add
(?w,r) alternative for VSUB64 types.
gcc/testsuite/ChangeLog:
* gcc.target/aarch64/aarch64-json-tunings/gp2fp-2.json: New JSON
tuning file.
* gcc.target/aarch64/simd/pr125716.c: New test.
---
gcc/config/aarch64/aarch64-simd.md | 1 +
.../gcc.target/aarch64/aarch64-json-tunings/gp2fp-2.json | 7 +++++++
gcc/testsuite/gcc.target/aarch64/simd/pr125716.c | 7 +++++++
3 files changed, 15 insertions(+)
create mode 100644
gcc/testsuite/gcc.target/aarch64/aarch64-json-tunings/gp2fp-2.json
create mode 100644 gcc/testsuite/gcc.target/aarch64/simd/pr125716.c
diff --git a/gcc/config/aarch64/aarch64-simd.md
b/gcc/config/aarch64/aarch64-simd.md
index b2e8fe3f6a9..ec7bebff0bd 100644
--- a/gcc/config/aarch64/aarch64-simd.md
+++ b/gcc/config/aarch64/aarch64-simd.md
@@ -304,6 +304,7 @@
[r , m ; load_4 , * ] ldr<size>\t%w0, %1
[w , w ; neon_logic , simd ] mov\t%0.8b, %1.8b
[w , m ; neon_load1_1reg , simd ] ldr\t%<vstype>0, %1
+ [?w, r ; f_mcr , * ] fmov\t%d0, %1
[w , Dz ; neon_move , simd ] movi\t%0.2d, #0
[m , rZ ; store_4 , * ] str<size>\t%w1, %0
[m , w ; neon_store1_1reg , simd ] str\t%<vstype>1, %0
diff --git a/gcc/testsuite/gcc.target/aarch64/aarch64-json-tunings/gp2fp-2.json
b/gcc/testsuite/gcc.target/aarch64/aarch64-json-tunings/gp2fp-2.json
new file mode 100644
index 00000000000..529efa84626
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/aarch64-json-tunings/gp2fp-2.json
@@ -0,0 +1,7 @@
+{
+ "tune_params": {
+ "regmove_cost": {
+ "GP2FP": 2
+ }
+ }
+}
diff --git a/gcc/testsuite/gcc.target/aarch64/simd/pr125716.c
b/gcc/testsuite/gcc.target/aarch64/simd/pr125716.c
new file mode 100644
index 00000000000..d38290cbbe9
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/simd/pr125716.c
@@ -0,0 +1,7 @@
+/* { dg-do compile } */
+/* { dg-options
"-muser-provided-CPU=${srcdir}/gcc.target/aarch64/aarch64-json-tunings/gp2fp-2.json
-O2 -fno-vect-cost-model -fweb" } */
+/* { dg-warning "JSON tuning file does not contain version information" "" {
target *-*-* } 0 } */
+
+double d;
+_Complex short cs;
+void foo() { cs *= d; }
--
2.43.0
