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authorRichard Henderson <richard.henderson@linaro.org>2020-11-03 13:20:21 -0800
committerRichard Henderson <richard.henderson@linaro.org>2020-11-04 10:35:40 -0800
commitc56caea3b2a4ef5d760266f554df0d92c5a45f87 (patch)
tree80fba4ec72139128960a1bbe052dc8432c0d8e83 /tcg/optimize.c
parentf14bed3fd4a17e1255e2ed6db1dfe50e654e601d (diff)
tcg: Revert "tcg/optimize: Flush data at labels not TCG_OPF_BB_END"
This reverts commit cd0372c515c4732d8bd3777cdd995c139c7ed7ea. The patch is incorrect in that it retains copies between globals and non-local temps, and non-local temps still die at the end of the BB. Failing test case for hppa: .globl _start _start: cmpiclr,= 0x24,%r19,%r0 cmpiclr,<> 0x2f,%r19,%r19 ---- 00010057 0001005b movi_i32 tmp0,$0x24 sub_i32 tmp1,tmp0,r19 mov_i32 tmp2,tmp0 mov_i32 tmp3,r19 movi_i32 tmp1,$0x0 ---- 0001005b 0001005f brcond_i32 tmp2,tmp3,eq,$L1 movi_i32 tmp0,$0x2f sub_i32 tmp1,tmp0,r19 mov_i32 tmp2,tmp0 mov_i32 tmp3,r19 movi_i32 tmp1,$0x0 mov_i32 r19,tmp1 setcond_i32 psw_n,tmp2,tmp3,ne set_label $L1 In this case, both copies of "mov_i32 tmp3,r19" are removed. The second because opt thought it was redundant. The first is removed later by liveness because tmp3 is known to be dead. This leaves the setcond_i32 with an uninitialized input. Revert the entire patch for 5.2, and a proper optimization across the branch may be considered for the next development cycle. Reported-by: qemu@igor2.repo.hu Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Diffstat (limited to 'tcg/optimize.c')
-rw-r--r--tcg/optimize.c35
1 files changed, 17 insertions, 18 deletions
diff --git a/tcg/optimize.c b/tcg/optimize.c
index 9952c28bdc..220f4601d5 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -1484,30 +1484,29 @@ void tcg_optimize(TCGContext *s)
}
}
}
- /* fall through */
+ goto do_reset_output;
default:
do_default:
- /*
- * Default case: we know nothing about operation (or were unable
- * to compute the operation result) so no propagation is done.
- */
- for (i = 0; i < nb_oargs; i++) {
- reset_temp(op->args[i]);
- /*
- * Save the corresponding known-zero bits mask for the
- * first output argument (only one supported so far).
- */
- if (i == 0) {
- arg_info(op->args[i])->mask = mask;
+ /* Default case: we know nothing about operation (or were unable
+ to compute the operation result) so no propagation is done.
+ We trash everything if the operation is the end of a basic
+ block, otherwise we only trash the output args. "mask" is
+ the non-zero bits mask for the first output arg. */
+ if (def->flags & TCG_OPF_BB_END) {
+ bitmap_zero(temps_used.l, nb_temps);
+ } else {
+ do_reset_output:
+ for (i = 0; i < nb_oargs; i++) {
+ reset_temp(op->args[i]);
+ /* Save the corresponding known-zero bits mask for the
+ first output argument (only one supported so far). */
+ if (i == 0) {
+ arg_info(op->args[i])->mask = mask;
+ }
}
}
break;
-
- case INDEX_op_set_label:
- /* Trash everything at the start of a new extended bb. */
- bitmap_zero(temps_used.l, nb_temps);
- break;
}
/* Eliminate duplicate and redundant fence instructions. */