[Qemu-devel] [PATCH v2 3/6] target/mips: Fix HI[ac] and LO[ac] 32-bit truncation with MIPS64 DSP ASE

[Fredrik Noring]

This change removes the 32-bit truncation of the HI[ac] and LO[ac]
special purpose registers when ac range from 1 to 3 for the instructions
MFHI, MFLO, MTHI and MTLO. The "MIPS Architecture for Programmers Volume
IV-e: MIPS DSP Module for MIPS64 Architecture" manual specifies that all
64 bits are copied in all cases:

   MFHI: GPR[rd]63..0 <- HI[ac]63..0
   MFLO: GPR[rd]63..0 <- LO[ac]63..0
   MTHI: HI[ac]63..0 <- GPR[rs]63..0
   MTLO: LO[ac]63..0 <- GPR[rs]63..0

Fixes: 4133498f8e53 ("Use correct acc value to index cpu_HI/cpu_LO rather than 
using a fix number")
Cc: Jia Liu <pro...@gmail.com>
Reported-by: Maciej W. Rozycki <ma...@linux-mips.org>
Signed-off-by: Fredrik Noring <nor...@nocrew.org>
---
 target/mips/translate.c | 36 ++++--------------------------------
 1 file changed, 4 insertions(+), 32 deletions(-)

diff --git a/target/mips/translate.c b/target/mips/translate.c
index 3ddd70043a..19ae7d2f1c 100644
--- a/target/mips/translate.c
+++ b/target/mips/translate.c
@@ -4409,49 +4409,21 @@ static void gen_HILO(DisasContext *ctx, uint32_t opc, 
int acc, int reg)
 
     switch (opc) {
     case OPC_MFHI:
-#if defined(TARGET_MIPS64)
-        if (acc != 0) {
-            tcg_gen_ext32s_tl(cpu_gpr[reg], cpu_HI[acc]);
-        } else
-#endif
-        {
-            tcg_gen_mov_tl(cpu_gpr[reg], cpu_HI[acc]);
-        }
+        tcg_gen_mov_tl(cpu_gpr[reg], cpu_HI[acc]);
         break;
     case OPC_MFLO:
-#if defined(TARGET_MIPS64)
-        if (acc != 0) {
-            tcg_gen_ext32s_tl(cpu_gpr[reg], cpu_LO[acc]);
-        } else
-#endif
-        {
-            tcg_gen_mov_tl(cpu_gpr[reg], cpu_LO[acc]);
-        }
+        tcg_gen_mov_tl(cpu_gpr[reg], cpu_LO[acc]);
         break;
     case OPC_MTHI:
         if (reg != 0) {
-#if defined(TARGET_MIPS64)
-            if (acc != 0) {
-                tcg_gen_ext32s_tl(cpu_HI[acc], cpu_gpr[reg]);
-            } else
-#endif
-            {
-                tcg_gen_mov_tl(cpu_HI[acc], cpu_gpr[reg]);
-            }
+            tcg_gen_mov_tl(cpu_HI[acc], cpu_gpr[reg]);
         } else {
             tcg_gen_movi_tl(cpu_HI[acc], 0);
         }
         break;
     case OPC_MTLO:
         if (reg != 0) {
-#if defined(TARGET_MIPS64)
-            if (acc != 0) {
-                tcg_gen_ext32s_tl(cpu_LO[acc], cpu_gpr[reg]);
-            } else
-#endif
-            {
-                tcg_gen_mov_tl(cpu_LO[acc], cpu_gpr[reg]);
-            }
+            tcg_gen_mov_tl(cpu_LO[acc], cpu_gpr[reg]);
         } else {
             tcg_gen_movi_tl(cpu_LO[acc], 0);
         }
-- 
2.18.1