[Qemu-devel] [PATCH 12/12] target-arm: fix neon shift helper functions

[Juha.Riihimaki]

Current code is broken at least on gcc 4.2, the result of a comparison  
"-1 >= sizeof(type) * 8" results true and causes wrong code path to be  
taken. The fix utilizes abs() function where applicable and otherwise  
adds a test to ensure both arguments are positive before making the  
aforementioned comparison.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Signed-off-by: Juha Riihimäki <address@hidden>
---
diff --git a/target-arm/neon_helper.c b/target-arm/neon_helper.c
index f32ecd6..0c95035 100644
--- a/target-arm/neon_helper.c
+++ b/target-arm/neon_helper.c
@@ -392,7 +392,7 @@ NEON_VOP(abd_u32, neon_u32, 1)
  #define NEON_FN(dest, src1, src2) do { \
      int8_t tmp; \
      tmp = (int8_t)src2; \
-    if (tmp >= sizeof(src1) * 8 || tmp <= -sizeof(src1) * 8) { \
+    if (abs(tmp) >= sizeof(src1) * 8) { \
          dest = 0; \
      } else if (tmp < 0) { \
          dest = src1 >> -tmp; \
@@ -420,7 +420,7 @@ uint64_t HELPER(neon_shl_u64)(uint64_t val,  
uint64_t shiftop)
  #define NEON_FN(dest, src1, src2) do { \
      int8_t tmp; \
      tmp = (int8_t)src2; \
-    if (tmp >= sizeof(src1) * 8) { \
+    if (tmp >= 0 && tmp >= sizeof(src1) * 8) { \
          dest = 0; \
      } else if (tmp <= -sizeof(src1) * 8) { \
          dest = src1 >> (sizeof(src1) * 8 - 1); \
@@ -453,7 +453,7 @@ uint64_t HELPER(neon_shl_s64)(uint64_t valop,  
uint64_t shiftop)
  #define NEON_FN(dest, src1, src2) do { \
      int8_t tmp; \
      tmp = (int8_t)src2; \
-    if (tmp >= sizeof(src1) * 8) { \
+    if (tmp >= 0 && tmp >= sizeof(src1) * 8) { \
          dest = 0; \
      } else if (tmp < -sizeof(src1) * 8) { \
          dest = src1 >> (sizeof(src1) * 8 - 1); \
@@ -494,7 +494,7 @@ uint64_t HELPER(neon_rshl_s64)(uint64_t valop,  
uint64_t shiftop)
  #define NEON_FN(dest, src1, src2) do { \
      int8_t tmp; \
      tmp = (int8_t)src2; \
-    if (tmp >= sizeof(src1) * 8 || tmp < -sizeof(src1) * 8) { \
+    if (abs(tmp) >= sizeof(src1) * 8) { \
          dest = 0; \
      } else if (tmp == -sizeof(src1) * 8) { \
          dest = src1 >> (tmp - 1); \
@@ -528,7 +528,7 @@ uint64_t HELPER(neon_rshl_u64)(uint64_t val,  
uint64_t shiftop)
  #define NEON_FN(dest, src1, src2) do { \
      int8_t tmp; \
      tmp = (int8_t)src2; \
-    if (tmp >= sizeof(src1) * 8) { \
+    if (tmp >= 0 && tmp >= sizeof(src1) * 8) { \
          if (src1) { \
              SET_QC(); \
              dest = ~0; \
@@ -579,7 +579,7 @@ uint64_t HELPER(neon_qshl_u64)(CPUState *env,  
uint64_t val, uint64_t shiftop)
  #define NEON_FN(dest, src1, src2) do { \
      int8_t tmp; \
      tmp = (int8_t)src2; \
-    if (tmp >= sizeof(src1) * 8) { \
+    if (tmp >= 0 && tmp >= sizeof(src1) * 8) { \
          if (src1) \
              SET_QC(); \
          dest = src1 >> 31; \

neon_helper.c.diff
Description: neon_helper.c.diff