In Perl_safesys{c,m,re}alloc(), defer dTHX for non-DEBUGING builds.

Under ithreads, dTHX expands to pthread_getspecific() [or something similarly
expensive], which the compiler can't optimise away. However, its return value
isn't needed unless the allocation fails. So defer the call, hence avoiding
it entirely on a successful allocation.

DEBUGING builds require the value of dTHX for debugging purposes, so we can't
postpone it for them. Unthreaded builds were never affected as they don't use
thread local storage for the interpreter context.

diff --git a/util.c b/util.c
index d5f0f1f..15dd162 100644 (file)
--- a/util.c
+++ b/util.c
@@ -75,7 +75,9 @@ S_write_no_mem(pTHX)
 Malloc_t
 Perl_safesysmalloc(MEM_SIZE size)
 {
+#ifdef DEBUGGING
     dTHX;
+#endif
     Malloc_t ptr;
 #ifdef HAS_64K_LIMIT
        if (size > 0xffff) {
@@ -118,10 +120,15 @@ Perl_safesysmalloc(MEM_SIZE size)
 #endif
        return ptr;
 }
-    else if (PL_nomemok)
-       return NULL;
     else {
-       return write_no_mem();
+#ifndef DEBUGGING
+       dTHX;
+#endif
+       if (PL_nomemok)
+           return NULL;
+       else {
+           return write_no_mem();
+       }
     }
     /*NOTREACHED*/
 }
@@ -131,7 +138,9 @@ Perl_safesysmalloc(MEM_SIZE size)
 Malloc_t
 Perl_safesysrealloc(Malloc_t where,MEM_SIZE size)
 {
+#ifdef DEBUGGING
     dTHX;
+#endif
     Malloc_t ptr;
 #if !defined(STANDARD_C) && !defined(HAS_REALLOC_PROTOTYPE) && !defined(PERL_MICRO)
     Malloc_t PerlMem_realloc();
@@ -213,10 +222,15 @@ Perl_safesysrealloc(Malloc_t where,MEM_SIZE size)
     if (ptr != NULL) {
        return ptr;
     }
-    else if (PL_nomemok)
-       return NULL;
     else {
-       return write_no_mem();
+#ifndef DEBUGGING
+       dTHX;
+#endif
+       if (PL_nomemok)
+           return NULL;
+       else {
+           return write_no_mem();
+       }
     }
     /*NOTREACHED*/
 }
@@ -226,7 +240,7 @@ Perl_safesysrealloc(Malloc_t where,MEM_SIZE size)
 Free_t
 Perl_safesysfree(Malloc_t where)
 {
-#if defined(PERL_IMPLICIT_SYS) || defined(PERL_TRACK_MEMPOOL)
+#if defined(DEBUGGING) && (defined(PERL_IMPLICIT_SYS) || defined(PERL_TRACK_MEMPOOL))
     dTHX;
 #else
     dVAR;
@@ -268,7 +282,9 @@ Perl_safesysfree(Malloc_t where)
 Malloc_t
 Perl_safesyscalloc(MEM_SIZE count, MEM_SIZE size)
 {
+#ifdef DEBUGGING
     dTHX;
+#endif
     Malloc_t ptr;
     MEM_SIZE total_size = 0;
 
@@ -330,9 +346,14 @@ Perl_safesyscalloc(MEM_SIZE count, MEM_SIZE size)
 #endif
        return ptr;
     }
-    else if (PL_nomemok)
-       return NULL;
-    return write_no_mem();
+    else {
+#ifndef DEBUGGING
+       dTHX;
+#endif
+       if (PL_nomemok)
+           return NULL;
+       return write_no_mem();
+    }
 }
 
 /* These must be defined when not using Perl's malloc for binary