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[Qemu-devel] [PATCH v2 08/10] target-arm: optimize thumb push/pop ops


From: juha . riihimaki
Subject: [Qemu-devel] [PATCH v2 08/10] target-arm: optimize thumb push/pop ops
Date: Sat, 24 Oct 2009 15:19:07 +0300

From: Juha Riihimäki <address@hidden>

Thumb push/pop instructions can be slightly optimized by loading the
register offset constant into a variable outside the register loop and
using the preloaded variable inside the loop instead of reloading the
offset value to a temporary variable on each loop iteration. This
causes less TCG ops to be generated for a Thumb push/pop instruction
if there are more than one register accessed, otherwise the amount of
generated TCG ops is the same.

Signed-off-by: Juha Riihimäki <address@hidden>
---
 target-arm/translate.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/target-arm/translate.c b/target-arm/translate.c
index 353f638..f262758 100644
--- a/target-arm/translate.c
+++ b/target-arm/translate.c
@@ -8596,6 +8596,7 @@ static void disas_thumb_insn(CPUState *env, DisasContext 
*s)
             if ((insn & (1 << 11)) == 0) {
                 tcg_gen_addi_i32(addr, addr, -offset);
             }
+            tmp2 = tcg_const_i32(4);
             for (i = 0; i < 8; i++) {
                 if (insn & (1 << i)) {
                     if (insn & (1 << 11)) {
@@ -8608,7 +8609,7 @@ static void disas_thumb_insn(CPUState *env, DisasContext 
*s)
                         gen_st32(tmp, addr, IS_USER(s));
                     }
                     /* advance to the next address.  */
-                    tcg_gen_addi_i32(addr, addr, 4);
+                    tcg_gen_add_i32(addr, addr, tmp2);
                 }
             }
             TCGV_UNUSED(tmp);
@@ -8623,8 +8624,9 @@ static void disas_thumb_insn(CPUState *env, DisasContext 
*s)
                     tmp = load_reg(s, 14);
                     gen_st32(tmp, addr, IS_USER(s));
                 }
-                tcg_gen_addi_i32(addr, addr, 4);
+                tcg_gen_add_i32(addr, addr, tmp2);
             }
+            tcg_temp_free_i32(tmp2);
             if ((insn & (1 << 11)) == 0) {
                 tcg_gen_addi_i32(addr, addr, -offset);
             }
-- 
1.6.5





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