Hi!
REE breaks the following testcase on KNL, where we only accept
QImode/HImode in k0-k7 registers (SImode/DImode is only supported
with -mavx512bw). We have
(set (reg:HI k0) (mem:HI ...))
...
(set (reg:DI rax) (zero_extend:DI (reg:HI k0)))
and we optimize it into:
(set (reg:DI rax) (zero_extend:DI (mem:HI ...)))
(set (reg:DI k0) (reg:DI rax))
The first insn is fine, but the latter is not really valid, kmovq
is only avx512bw, only kmovw is avx512f.
Fixed by consulting HARD_REGNO_MODE_OK in addition to comparing
HARD_REGNO_NREGS.
This change affects just
gcc.target/i386/{avx512{f,dq}-pr77476.c,avx512f-klogic-2.c,pr78132.c}
testcases, in all cases it is about k0 or k1 register and SImode or DImode.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2016-10-27 Jakub Jelinek <ja...@redhat.com>
PR rtl-optimization/78132
* ree.c (combine_reaching_defs): Give up if copy_needed and
!HARD_REGNO_MODE_OK (REGNO (src_reg), dst_mode).
* gcc.target/i386/pr78132.c: New test.
--- gcc/ree.c.jj 2016-10-21 11:36:33.000000000 +0200
+++ gcc/ree.c 2016-10-27 18:43:00.899215537 +0200
@@ -788,6 +788,11 @@ combine_reaching_defs (ext_cand *cand, c
machine_mode dst_mode = GET_MODE (SET_DEST (PATTERN (cand->insn)));
rtx src_reg = get_extended_src_reg (SET_SRC (PATTERN (cand->insn)));
+ /* Ensure we can use the src_reg in dst_mode (needed for
+ the (set (reg1) (reg2)) insn mentioned above). */
+ if (!HARD_REGNO_MODE_OK (REGNO (src_reg), dst_mode))
+ return false;
+
/* Ensure the number of hard registers of the copy match. */
if (HARD_REGNO_NREGS (REGNO (src_reg), dst_mode)
!= HARD_REGNO_NREGS (REGNO (src_reg), GET_MODE (src_reg)))
--- gcc/testsuite/gcc.target/i386/pr78132.c.jj 2016-10-27 18:48:25.944128889
+0200
+++ gcc/testsuite/gcc.target/i386/pr78132.c 2016-10-27 18:48:53.538781368
+0200
@@ -0,0 +1,20 @@
+/* PR rtl-optimization/78132 */
+/* { dg-do compile } */
+/* { dg-options "-O3 -mavx512f -mno-avx512bw -mno-avx512dq -masm=att" } */
+/* { dg-final { scan-assembler-not "kmov\[dq]\t" } } */
+
+unsigned short c;
+char a, d, f, b;
+short e;
+long g;
+
+int
+main ()
+{
+ g = c;
+ f = c & e;
+ d = c & a | e;
+ if (a)
+ b = c;
+ return 0;
+}
Jakub
