The TST instruction no longer matches in all cases due to changes in
Combine. The fix is simple, we now need to allow a subreg as well when
selecting the cc_mode. This fixes the tst_5.c and tst_6.c failures.
AArch64 regress & bootstrap OK.
ChangeLog:
2019-01-23 Wilco Dijkstra <wdijk...@arm.com>
PR rtl-optimization/87763
* config/aarch64/aarch64.c (aarch64_select_cc_mode):
Allow SUBREG when matching CC_NZmode compare.
--
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index
a0006dc1f8a921dd83209d4404132a1fe3cfcd1e..237428d28b4f20ddfefee83ed020e209011147a0
100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -7120,7 +7120,7 @@ aarch64_select_cc_mode (RTX_CODE code, rtx x, rtx y)
/* Equality comparisons of short modes against zero can be performed
using the TST instruction with the appropriate bitmask. */
- if (y == const0_rtx && REG_P (x)
+ if (y == const0_rtx && (REG_P (x) || SUBREG_P (x))
&& (code == EQ || code == NE)
&& (GET_MODE (x) == HImode || GET_MODE (x) == QImode))
return CC_NZmode;
