Re: [PATCH 4/8] target/ppc: Evaluate TARGET_BIG_ENDIAN at compile time

[Pierrick Bouvier]

On 4/17/25 06:10, Philippe Mathieu-Daudé wrote:
Rather than evaluating TARGET_BIG_ENDIAN at preprocessing
time via #ifdef'ry, do it in C at compile time
Signed-off-by: Philippe Mathieu-Daudé <phi...@linaro.org>
---
  target/ppc/cpu_init.c   | 12 ++++++------
  target/ppc/mem_helper.c |  6 +-----
  target/ppc/translate.c  |  6 +-----
  3 files changed, 8 insertions(+), 16 deletions(-)

diff --git a/target/ppc/cpu_init.c b/target/ppc/cpu_init.c
index 077991ed535..bbab411a07c 100644
--- a/target/ppc/cpu_init.c
+++ b/target/ppc/cpu_init.c
@@ -7262,14 +7262,14 @@ static void ppc_cpu_reset_hold(Object *obj, ResetType 
type)
  #if defined(TARGET_PPC64)
      msr |= (target_ulong)1 << MSR_TM; /* Transactional memory */
  #endif
-#if !TARGET_BIG_ENDIAN
-    msr |= (target_ulong)1 << MSR_LE; /* Little-endian user mode */
-    if (!((env->msr_mask >> MSR_LE) & 1)) {
-        fprintf(stderr, "Selected CPU does not support little-endian.\n");
-        exit(1);
+    if (!TARGET_BIG_ENDIAN) {
+        msr |= (target_ulong)1 << MSR_LE; /* Little-endian user mode */
+        if (!((env->msr_mask >> MSR_LE) & 1)) {
+            fprintf(stderr, "Selected CPU does not support little-endian.\n");
+            exit(1);
+        }
      }
  #endif
-#endif
  
  #if defined(TARGET_PPC64)
      if (mmu_is_64bit(env->mmu_model)) {
diff --git a/target/ppc/mem_helper.c b/target/ppc/mem_helper.c
index d7e8d678f4b..cc3ed29a35b 100644
--- a/target/ppc/mem_helper.c
+++ b/target/ppc/mem_helper.c
@@ -32,11 +32,7 @@
  
  static inline bool needs_byteswap(const CPUPPCState *env)
  {
-#if TARGET_BIG_ENDIAN
-  return FIELD_EX64(env->msr, MSR, LE);
-#else
-  return !FIELD_EX64(env->msr, MSR, LE);
-#endif
+  return TARGET_BIG_ENDIAN ^ FIELD_EX64(env->msr, MSR, LE);
  }
  
  /*****************************************************************************/
diff --git a/target/ppc/translate.c b/target/ppc/translate.c
index 399107d319a..828b850b40e 100644
--- a/target/ppc/translate.c
+++ b/target/ppc/translate.c
@@ -213,11 +213,7 @@ struct DisasContext {
  /* Return true iff byteswap is needed in a scalar memop */
  static inline bool need_byteswap(const DisasContext *ctx)
  {
-#if TARGET_BIG_ENDIAN
-     return ctx->le_mode;
-#else
-     return !ctx->le_mode;
-#endif
+     return TARGET_BIG_ENDIAN ^ ctx->le_mode;

Maybe I'm missing something, but with {TARGET_BIG_ENDIAN: 1, 
ctx->le_mode: 1}, it would return 0, while it should be 1 instead.

It would be more readable to use a if or a ternary expression.
Same for previous function needs_byteswap.

  }
  
  /* True when active word size < size of target_long.  */