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Re: [PATCH v2 33/81] tcg/i386: Handle all 8-bit extensions for i686


From: Philippe Mathieu-Daudé
Subject: Re: [PATCH v2 33/81] tcg/i386: Handle all 8-bit extensions for i686
Date: Wed, 15 Jan 2025 21:13:25 +0100
User-agent: Mozilla Thunderbird

On 7/1/25 09:00, Richard Henderson wrote:
When we generalize {s}extract_i32, we'll lose the
specific register constraints on ext8u and ext8s.
It's just as easy to emit a couple of insns instead.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
  tcg/i386/tcg-target.c.inc | 23 +++++++++++++++++++----
  1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/tcg/i386/tcg-target.c.inc b/tcg/i386/tcg-target.c.inc
index e51269f81d..047c5da81c 100644
--- a/tcg/i386/tcg-target.c.inc
+++ b/tcg/i386/tcg-target.c.inc
@@ -1329,16 +1329,31 @@ static inline void tcg_out_rolw_8(TCGContext *s, int 
reg)
static void tcg_out_ext8u(TCGContext *s, TCGReg dest, TCGReg src)
  {
-    /* movzbl */
-    tcg_debug_assert(src < 4 || TCG_TARGET_REG_BITS == 64);
+    if (TCG_TARGET_REG_BITS == 32 && src >= 4) {
+        tcg_out_mov(s, TCG_TYPE_I32, dest, src);
+        if (dest >= 4) {
+            tcg_out_modrm(s, OPC_ARITH_EvIz, ARITH_AND, dest);
+            tcg_out32(s, 0xff);
+            return;
+        }
+        src = dest;
+    }
      tcg_out_modrm(s, OPC_MOVZBL + P_REXB_RM, dest, src);
  }
static void tcg_out_ext8s(TCGContext *s, TCGType type, TCGReg dest, TCGReg src)
  {
      int rexw = type == TCG_TYPE_I32 ? 0 : P_REXW;
-    /* movsbl */
-    tcg_debug_assert(src < 4 || TCG_TARGET_REG_BITS == 64);
+
+    if (TCG_TARGET_REG_BITS == 32 && src >= 4) {
+        tcg_out_mov(s, TCG_TYPE_I32, dest, src);
+        if (dest >= 4) {
+            tcg_out_shifti(s, SHIFT_SHL, dest, 24);
+            tcg_out_shifti(s, SHIFT_SAR, dest, 24);
+            return;
+        }
+        src = dest;
+    }
      tcg_out_modrm(s, OPC_MOVSBL + P_REXB_RM + rexw, dest, src);
  }

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




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