[Qemu-devel] [PULL 27/52] target-ppc: Bug Fix: rlwnm

[Alexander Graf]

From: Tom Musta <address@hidden>

The rlwnm specification includes the ROTL32 operation, which is defined
to be a left rotation of two copies of the least significant 32 bits of
the source GPR.

The current implementation is incorrect on 64-bit implementations in that
it rotates a single copy of the least significant 32 bits, padding with
zeroes in the most significant bits.

Fix the code to properly implement this ROTL32 operation.

Example:

R3 = 0000000000000002
R4 = 7FFFFFFFFFFFFFFF
rlwnm 3,3,4,31,16
R3 expected : 0000000100000001
R3 actual   : 0000000000000001 (without this patch)

Signed-off-by: Tom Musta <address@hidden>
Signed-off-by: Alexander Graf <address@hidden>
---
 target-ppc/translate.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/target-ppc/translate.c b/target-ppc/translate.c
index 44a8e1e..be7d40b 100644
--- a/target-ppc/translate.c
+++ b/target-ppc/translate.c
@@ -1698,7 +1698,7 @@ static void gen_rlwnm(DisasContext *ctx)
     uint32_t mb, me;
     TCGv t0;
 #if defined(TARGET_PPC64)
-    TCGv_i32 t1, t2;
+    TCGv t1;
 #endif
 
     mb = MB(ctx->opcode);
@@ -1706,14 +1706,11 @@ static void gen_rlwnm(DisasContext *ctx)
     t0 = tcg_temp_new();
     tcg_gen_andi_tl(t0, cpu_gpr[rB(ctx->opcode)], 0x1f);
 #if defined(TARGET_PPC64)
-    t1 = tcg_temp_new_i32();
-    t2 = tcg_temp_new_i32();
-    tcg_gen_trunc_i64_i32(t1, cpu_gpr[rS(ctx->opcode)]);
-    tcg_gen_trunc_i64_i32(t2, t0);
-    tcg_gen_rotl_i32(t1, t1, t2);
-    tcg_gen_extu_i32_i64(t0, t1);
-    tcg_temp_free_i32(t1);
-    tcg_temp_free_i32(t2);
+    t1 = tcg_temp_new_i64();
+    tcg_gen_deposit_i64(t1, cpu_gpr[rS(ctx->opcode)],
+        cpu_gpr[rS(ctx->opcode)], 32, 32);
+    tcg_gen_rotl_i64(t0, t1, t0);
+    tcg_temp_free_i64(t1);
 #else
     tcg_gen_rotl_i32(t0, cpu_gpr[rS(ctx->opcode)], t0);
 #endif
@@ -1724,6 +1721,9 @@ static void gen_rlwnm(DisasContext *ctx)
 #endif
         tcg_gen_andi_tl(cpu_gpr[rA(ctx->opcode)], t0, MASK(mb, me));
     } else {
+#if defined(TARGET_PPC64)
+        tcg_gen_andi_tl(t0, t0, MASK(32, 63));
+#endif
         tcg_gen_mov_tl(cpu_gpr[rA(ctx->opcode)], t0);
     }
     tcg_temp_free(t0);
-- 
1.8.1.4