[Qemu-devel] [5546] CRIS: Add branch-free versions of abs, lsl, lsr and asr.

[Edgar E. Iglesias]

Revision: 5546
          http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=5546
Author:   edgar_igl
Date:     2008-10-27 12:39:30 +0000 (Mon, 27 Oct 2008)

Log Message:
-----------
CRIS: Add branch-free versions of abs, lsl, lsr and asr.

Signed-off-by: Edgar E. Iglesias <address@hidden>

Modified Paths:
--------------
    trunk/target-cris/translate.c

Modified: trunk/target-cris/translate.c
===================================================================
--- trunk/target-cris/translate.c       2008-10-26 23:18:06 UTC (rev 5545)
+++ trunk/target-cris/translate.c       2008-10-27 12:39:30 UTC (rev 5546)
@@ -229,41 +229,52 @@
 
 static void t_gen_lsl(TCGv d, TCGv a, TCGv b)
 {
-       int l1;
+       TCGv t0, t_31;
 
-       l1 = gen_new_label();
-       /* Speculative shift. */
+       t0 = tcg_temp_new(TCG_TYPE_TL);
+       t_31 = tcg_temp_new(TCG_TYPE_TL);
        tcg_gen_shl_tl(d, a, b);
-       tcg_gen_brcondi_tl(TCG_COND_LEU, b, 31, l1);
-       /* Clear dst if shift operands were to large.  */
-       tcg_gen_movi_tl(d, 0);
-       gen_set_label(l1);
+
+       tcg_gen_movi_tl(t_31, 31);
+       tcg_gen_sub_tl(t0, t_31, b);
+       tcg_gen_sar_tl(t0, t0, t_31);
+       tcg_gen_and_tl(t0, t0, d);
+       tcg_gen_xor_tl(d, d, t0);
+       tcg_temp_free(t0);
+       tcg_temp_free(t_31);
 }
 
 static void t_gen_lsr(TCGv d, TCGv a, TCGv b)
 {
-       int l1;
+       TCGv t0, t_31;
 
-       l1 = gen_new_label();
-       /* Speculative shift. */
+       t0 = tcg_temp_new(TCG_TYPE_TL);
+       t_31 = tcg_temp_new(TCG_TYPE_TL);
        tcg_gen_shr_tl(d, a, b);
-       tcg_gen_brcondi_tl(TCG_COND_LEU, b, 31, l1);
-       /* Clear dst if shift operands were to large.  */
-       tcg_gen_movi_tl(d, 0);
-       gen_set_label(l1);
+
+       tcg_gen_movi_tl(t_31, 31);
+       tcg_gen_sub_tl(t0, t_31, b);
+       tcg_gen_sar_tl(t0, t0, t_31);
+       tcg_gen_and_tl(t0, t0, d);
+       tcg_gen_xor_tl(d, d, t0);
+       tcg_temp_free(t0);
+       tcg_temp_free(t_31);
 }
 
 static void t_gen_asr(TCGv d, TCGv a, TCGv b)
 {
-       int l1;
+       TCGv t0, t_31;
 
-       l1 = gen_new_label();
-       /* Speculative shift. */
+       t0 = tcg_temp_new(TCG_TYPE_TL);
+       t_31 = tcg_temp_new(TCG_TYPE_TL);
        tcg_gen_sar_tl(d, a, b);
-       tcg_gen_brcondi_tl(TCG_COND_LEU, b, 31, l1);
-       /* Clear dst if shift operands were to large.  */
-       tcg_gen_sar_tl(d, a, tcg_const_tl(30));
-       gen_set_label(l1);
+
+       tcg_gen_movi_tl(t_31, 31);
+       tcg_gen_sub_tl(t0, t_31, b);
+       tcg_gen_sar_tl(t0, t0, t_31);
+       tcg_gen_or_tl(d, d, t0);
+       tcg_temp_free(t0);
+       tcg_temp_free(t_31);
 }
 
 /* 64-bit signed mul, lower result in d and upper in d2.  */
@@ -1777,20 +1788,20 @@
 
 static unsigned int dec_abs_r(DisasContext *dc)
 {
-       int l1;
+       TCGv t0;
 
        DIS(fprintf (logfile, "abs $r%u, $r%u\n",
                    dc->op1, dc->op2));
        cris_cc_mask(dc, CC_MASK_NZ);
-       dec_prep_move_r(dc, dc->op1, dc->op2, 4, 0, cpu_T[1]);
 
-       /* TODO: consider a branch free approach.  */
-       l1 = gen_new_label();
-       tcg_gen_brcondi_tl(TCG_COND_GE, cpu_T[1], 0, l1);
-       tcg_gen_neg_tl(cpu_T[1], cpu_T[1]);
-       gen_set_label(l1);
+       t0 = tcg_temp_new(TCG_TYPE_TL);
+       tcg_gen_sari_tl(t0, cpu_R[dc->op1], 31);
+       tcg_gen_xor_tl(cpu_R[dc->op2], cpu_R[dc->op1], t0);
+       tcg_gen_sub_tl(cpu_R[dc->op2], cpu_R[dc->op2], t0);
+       tcg_temp_free(t0);
+
        cris_alu(dc, CC_OP_MOVE,
-                   cpu_R[dc->op2], cpu_R[dc->op2], cpu_T[1], 4);
+                   cpu_R[dc->op2], cpu_R[dc->op2], cpu_R[dc->op2], 4);
        return 2;
 }