Re: [PATCH v3 19/38] tcg/aarch64: Generate CBNZ for TSTNE of UINT32_MAX

[Philippe Mathieu-Daudé]

On 10/1/24 23:43, Richard Henderson wrote:

... and the inverse, CBZ for TSTEQ.

Suggested-by: Paolo Bonzini <pbonz...@redhat.com>
Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
---
  tcg/aarch64/tcg-target.c.inc | 8 ++++++++
  1 file changed, 8 insertions(+)

diff --git a/tcg/aarch64/tcg-target.c.inc b/tcg/aarch64/tcg-target.c.inc
index 55225313ad..0c98c48f68 100644
--- a/tcg/aarch64/tcg-target.c.inc
+++ b/tcg/aarch64/tcg-target.c.inc
@@ -1453,6 +1453,7 @@ static void tcg_out_brcond(TCGContext *s, TCGType ext, 
TCGCond c, TCGArg a,
          break;
      case TCG_COND_LT:
      case TCG_COND_GE:
+        /* cmp xN,0; b.mi L -> tbnz xN,63,L */
          if (b_const && b == 0) {
              c = (c == TCG_COND_LT ? TCG_COND_TSTNE : TCG_COND_TSTEQ);

This comment ...

              tbit = ext ? 63 : 31;
@@ -1461,6 +1462,13 @@ static void tcg_out_brcond(TCGContext *s, TCGType ext, 
TCGCond c, TCGArg a,
          break;
      case TCG_COND_TSTEQ:
      case TCG_COND_TSTNE:
+        /* tst xN,0xffffffff; b.ne L -> cbnz wN,L */
+        if (b_const && b == UINT32_MAX) {
+            ext = TCG_TYPE_I32;
+            need_cmp = false;
+            break;
+        }
+        /* tst xN,1<<B; b.ne L -> tbnz xN,B,L */

... and this one belong to the previous patch. Otherwise:

Reviewed-by: Philippe Mathieu-Daudé <phi...@linaro.org>

          if (b_const && is_power_of_2(b)) {
              tbit = ctz64(b);
              need_cmp = false;