Expand as branch over move if not supported in the ISA.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20231026041404.1229328-3-richard.henderson@linaro.org>
---
 tcg/mips/tcg-target.h     |  4 ++--
 tcg/mips/tcg-target.c.inc | 19 ++++++++++++++-----
 2 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/tcg/mips/tcg-target.h b/tcg/mips/tcg-target.h
index c0576f66d7..0a4083f0d9 100644
--- a/tcg/mips/tcg-target.h
+++ b/tcg/mips/tcg-target.h
@@ -154,7 +154,7 @@ extern bool use_mips32r2_instructions;
 #endif
 
 /* optional instructions detected at runtime */
-#define TCG_TARGET_HAS_movcond_i32      use_movnz_instructions
+#define TCG_TARGET_HAS_movcond_i32      1
 #define TCG_TARGET_HAS_bswap16_i32      use_mips32r2_instructions
 #define TCG_TARGET_HAS_deposit_i32      use_mips32r2_instructions
 #define TCG_TARGET_HAS_extract_i32      use_mips32r2_instructions
@@ -169,7 +169,7 @@ extern bool use_mips32r2_instructions;
 #define TCG_TARGET_HAS_qemu_st8_i32     0
 
 #if TCG_TARGET_REG_BITS == 64
-#define TCG_TARGET_HAS_movcond_i64      use_movnz_instructions
+#define TCG_TARGET_HAS_movcond_i64      1
 #define TCG_TARGET_HAS_bswap16_i64      use_mips32r2_instructions
 #define TCG_TARGET_HAS_bswap32_i64      use_mips32r2_instructions
 #define TCG_TARGET_HAS_bswap64_i64      use_mips32r2_instructions
diff --git a/tcg/mips/tcg-target.c.inc b/tcg/mips/tcg-target.c.inc
index 89681f00fe..82b078b9c5 100644
--- a/tcg/mips/tcg-target.c.inc
+++ b/tcg/mips/tcg-target.c.inc
@@ -1070,13 +1070,22 @@ static void tcg_out_movcond(TCGContext *s, TCGCond cond, TCGReg ret,
         if (v2 != 0) {
             tcg_out_opc_reg(s, OPC_OR, ret, ret, TCG_TMP1);
         }
-    } else {
+        return;
+    }
+
+    /* This should be guaranteed via constraints */
+    tcg_debug_assert(v2 == ret);
+
+    if (use_movnz_instructions) {
         MIPSInsn m_opc = eqz ? OPC_MOVZ : OPC_MOVN;
-
         tcg_out_opc_reg(s, m_opc, ret, v1, c1);
-
-        /* This should be guaranteed via constraints */
-        tcg_debug_assert(v2 == ret);
+    } else {
+        /* Invert the condition in order to branch over the move. */
+        MIPSInsn b_opc = eqz ? OPC_BNE : OPC_BEQ;
+        tcg_out_opc_imm(s, b_opc, c1, TCG_REG_ZERO, 2);
+        tcg_out_nop(s);
+        /* Open-code tcg_out_mov, without the nop-move check. */
+        tcg_out_opc_reg(s, OPC_OR, ret, v1, TCG_REG_ZERO);
     }
 }
 
-- 
2.34.1