[PATCH 1/4] tcg: Canonicalize subi to addi during opcode generation

[Richard Henderson]

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 tcg/tcg-op.c | 25 +++++++++----------------
 1 file changed, 9 insertions(+), 16 deletions(-)

diff --git a/tcg/tcg-op.c b/tcg/tcg-op.c
index 59deb3cbbb..3fce9bd8f4 100644
--- a/tcg/tcg-op.c
+++ b/tcg/tcg-op.c
@@ -147,12 +147,7 @@ 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_andi_i32(TCGv_i32 ret, TCGv_i32 arg1, int32_t arg2)
@@ -1258,6 +1253,13 @@ void tcg_gen_add_i64(TCGv_i64 ret, TCGv_i64 arg1, 
TCGv_i64 arg2)
 
 void tcg_gen_sub_i64(TCGv_i64 ret, TCGv_i64 arg1, TCGv_i64 arg2)
 {
+    TCGTemp *ts2 = tcgv_i64_temp(arg2);
+
+    /* Canonicalize subi into addi. */
+    if (ts2->kind == TEMP_CONST) {
+        tcg_gen_addi_i64(ret, arg1, -ts2->val);
+        return;
+    }
     tcg_gen_sub2_i32(TCGV_LOW(ret), TCGV_HIGH(ret), TCGV_LOW(arg1),
                      TCGV_HIGH(arg1), TCGV_LOW(arg2), TCGV_HIGH(arg2));
 }
@@ -1354,16 +1356,7 @@ 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_andi_i64(TCGv_i64 ret, TCGv_i64 arg1, int64_t arg2)
-- 
2.34.1