From: Richard Henderson <richard.henderson@linaro.org>
Date: Thu, 26 Oct 2023 01:39:42 +0000 (-0700)
Subject: tcg: Canonicalize subi to addi during opcode generation
X-Git-Tag: v8.2.0-rc0~26^2~3
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=1551004eeb4436a163472c3b5b108a60766e74cb;p=thirdparty%2Fqemu.git

tcg: Canonicalize subi to addi during opcode generation

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20231026013945.1152174-2-richard.henderson@linaro.org>
---

diff --git a/tcg/tcg-op.c b/tcg/tcg-op.c
index de096a6f937..aa6bc6f57dd 100644
--- a/tcg/tcg-op.c
+++ b/tcg/tcg-op.c
@@ -372,12 +372,7 @@ void tcg_gen_subfi_i32(TCGv_i32 ret, int32_t arg1, TCGv_i32 arg2)
 
 void tcg_gen_subi_i32(TCGv_i32 ret, TCGv_i32 arg1, int32_t arg2)
 {
-    /* some cases can be optimized here */
-    if (arg2 == 0) {
-        tcg_gen_mov_i32(ret, arg1);
-    } else {
-        tcg_gen_sub_i32(ret, arg1, tcg_constant_i32(arg2));
-    }
+    tcg_gen_addi_i32(ret, arg1, -arg2);
 }
 
 void tcg_gen_neg_i32(TCGv_i32 ret, TCGv_i32 arg)
@@ -1752,16 +1747,7 @@ void tcg_gen_subfi_i64(TCGv_i64 ret, int64_t arg1, TCGv_i64 arg2)
 
 void tcg_gen_subi_i64(TCGv_i64 ret, TCGv_i64 arg1, int64_t arg2)
 {
-    /* some cases can be optimized here */
-    if (arg2 == 0) {
-        tcg_gen_mov_i64(ret, arg1);
-    } else if (TCG_TARGET_REG_BITS == 64) {
-        tcg_gen_sub_i64(ret, arg1, tcg_constant_i64(arg2));
-    } else {
-        tcg_gen_sub2_i32(TCGV_LOW(ret), TCGV_HIGH(ret),
-                         TCGV_LOW(arg1), TCGV_HIGH(arg1),
-                         tcg_constant_i32(arg2), tcg_constant_i32(arg2 >> 32));
-    }
+    tcg_gen_addi_i64(ret, arg1, -arg2);
 }
 
 void tcg_gen_neg_i64(TCGv_i64 ret, TCGv_i64 arg)