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[Qemu-devel] [PATCH 08/11] target-m68k: Optimize some comparisons
From: |
Richard Henderson |
Subject: |
[Qemu-devel] [PATCH 08/11] target-m68k: Optimize some comparisons |
Date: |
Fri, 14 Aug 2015 07:59:23 -0700 |
Signed-off-by: Richard Henderson <address@hidden>
---
target-m68k/translate.c | 108 +++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 102 insertions(+), 6 deletions(-)
diff --git a/target-m68k/translate.c b/target-m68k/translate.c
index 28c3e1e..6f60c6f 100644
--- a/target-m68k/translate.c
+++ b/target-m68k/translate.c
@@ -793,10 +793,43 @@ static void gen_cc_cond(DisasCompare *c, DisasContext *s,
int cond)
{
TCGv tmp, tmp2;
TCGCond tcond;
+ CCOp op = s->cc_op;
- /* TODO: Optimize compare/branch pairs rather than always flushing
- flag state to CC_OP_FLAGS. */
- gen_flush_flags(s);
+ /* The CC_OP_CMP form can handle most normal comparisons directly. */
+ if (op == CC_OP_CMP) {
+ c->g1 = c->g2 = 1;
+ c->v1 = QREG_CC_N;
+ c->v2 = QREG_CC_V;
+ switch (cond) {
+ case 2: /* HI */
+ case 3: /* LS */
+ tcond = TCG_COND_LEU;
+ goto done;
+ case 4: /* CC */
+ case 5: /* CS */
+ tcond = TCG_COND_LTU;
+ goto done;
+ case 6: /* NE */
+ case 7: /* EQ */
+ tcond = TCG_COND_EQ;
+ goto done;
+ case 10: /* PL */
+ case 11: /* MI */
+ c->g1 = c->g2 = 0;
+ c->v2 = tcg_const_i32(0);
+ c->v1 = tmp = tcg_temp_new();
+ tcg_gen_sub_i32(tmp, QREG_CC_N, QREG_CC_V);
+ /* fallthru */
+ case 12: /* GE */
+ case 13: /* LT */
+ tcond = TCG_COND_LT;
+ goto done;
+ case 14: /* GT */
+ case 15: /* LE */
+ tcond = TCG_COND_LE;
+ goto done;
+ }
+ }
c->g1 = 1;
c->g2 = 0;
@@ -807,7 +840,71 @@ static void gen_cc_cond(DisasCompare *c, DisasContext *s,
int cond)
case 1: /* F */
c->v1 = c->v2;
tcond = TCG_COND_NEVER;
+ goto done;
+ case 14: /* GT (!(Z || (N ^ V))) */
+ case 15: /* LE (Z || (N ^ V)) */
+ /* Logic operations clear V, which simplifies LE to (Z || N),
+ and since Z and N are co-located, this becomes a normal
+ comparison vs N. */
+ if (op == CC_OP_LOGIC) {
+ c->v1 = QREG_CC_N;
+ tcond = TCG_COND_LE;
+ goto done;
+ }
+ break;
+ case 12: /* GE (!(N ^ V)) */
+ case 13: /* LT (N ^ V) */
+ /* Logic operations clear V, which simplifies this to N. */
+ if (op != CC_OP_LOGIC) {
+ break;
+ }
+ /* fallthru */
+ case 10: /* PL (!N) */
+ case 11: /* MI (N) */
+ /* Several cases represent N normally. */
+ if (op == CC_OP_ADD || op == CC_OP_SUB || op == CC_OP_LOGIC) {
+ c->v1 = QREG_CC_N;
+ tcond = TCG_COND_LT;
+ goto done;
+ }
+ break;
+ case 6: /* NE (!Z) */
+ case 7: /* EQ (Z) */
+ /* Some cases fold Z into N. */
+ if (op == CC_OP_ADD || op == CC_OP_SUB || op == CC_OP_LOGIC) {
+ tcond = TCG_COND_EQ;
+ c->v1 = QREG_CC_N;
+ goto done;
+ }
break;
+ case 4: /* CC (!C) */
+ case 5: /* CS (C) */
+ /* Some cases fold C into X. */
+ if (op == CC_OP_ADD || op == CC_OP_SUB) {
+ tcond = TCG_COND_NE;
+ c->v1 = QREG_CC_X;
+ goto done;
+ }
+ /* fallthru */
+ case 8: /* VC (!V) */
+ case 9: /* VS (V) */
+ /* Logic operations clear V and C. */
+ if (op == CC_OP_LOGIC) {
+ tcond = TCG_COND_NEVER;
+ c->v2 = c->v1;
+ }
+ break;
+ }
+
+ /* Otherwise, flush flag state to CC_OP_FLAGS. */
+ gen_flush_flags(s);
+
+ switch (cond) {
+ case 0: /* T */
+ case 1: /* F */
+ default:
+ /* Invalid, or handled above. */
+ abort();
case 2: /* HI (!C && !Z) -> !(C || Z)*/
case 3: /* LS (C || Z) */
c->v1 = tmp = tcg_temp_new();
@@ -855,10 +952,9 @@ static void gen_cc_cond(DisasCompare *c, DisasContext *s,
int cond)
tcg_temp_free(tmp2);
tcond = TCG_COND_LT;
break;
- default:
- /* Should ever happen. */
- abort();
}
+
+ done:
if ((cond & 1) == 0) {
tcond = tcg_invert_cond(tcond);
}
--
2.4.3
- [Qemu-devel] [PATCH 00/11] Proposed format for m68k flags, Richard Henderson, 2015/08/14
- [Qemu-devel] [PATCH 01/11] target-m68k: Print flags properly, Richard Henderson, 2015/08/14
- [Qemu-devel] [PATCH 02/11] target-m68k: Some fixes to SR and flags management, Richard Henderson, 2015/08/14
- [Qemu-devel] [PATCH 03/11] target-m68k: Remove incorrect clearing of cc_x, Richard Henderson, 2015/08/14
- [Qemu-devel] [PATCH 04/11] target-m68k: Replace helper_xflag_lt with setcond, Richard Henderson, 2015/08/14
- [Qemu-devel] [PATCH 07/11] target-m68k: Use setcond for scc, Richard Henderson, 2015/08/14
- [Qemu-devel] [PATCH 08/11] target-m68k: Optimize some comparisons,
Richard Henderson <=
- [Qemu-devel] [PATCH 09/11] target-m68k: Optimize gen_flush_flags, Richard Henderson, 2015/08/14
- [Qemu-devel] [PATCH 10/11] target-m68k: Inline shifts, Richard Henderson, 2015/08/14
- [Qemu-devel] [PATCH 06/11] target-m68k: Introduce DisasCompare, Richard Henderson, 2015/08/14
- [Qemu-devel] [PATCH 11/11] target-m68k: Inline addx, subx, negx, Richard Henderson, 2015/08/14
- [Qemu-devel] [PATCH 05/11] target-m68k: Reorg flags handling, Richard Henderson, 2015/08/14
- Re: [Qemu-devel] [PATCH 00/11] Proposed format for m68k flags, Laurent Vivier, 2015/08/14