[gcc r12-5133] Apply pattern initialization only when have_insn_for return true.

[gcc r12-5133] Apply pattern initialization only when have_insn_for return true.

[Qing Zhao]

https://gcc.gnu.org/g:1c04af34c9c66d8ed9f6c12c97dd064238ddfa20

commit r12-5133-g1c04af34c9c66d8ed9f6c12c97dd064238ddfa20
Author: Qing Zhao <qing.zhao@oracle.com>
Date:   Wed Nov 10 17:59:31 2021 +0000

    Apply pattern initialization only when have_insn_for return true.
    
    For -ftrivial-auto-var-init=pattern, initialize the variable with patterns only
    when have_insn_for (SET, mode) return true.  Otherwise initialize it with zeros.
    with this change, _Complex long double on X86 is initialized to zero for
    pattern initialization.
    
    gcc/ChangeLog:
    
    2021-11-10  qing zhao  <qing.zhao@oracle.com>
    
            * internal-fn.c (expand_DEFERRED_INIT): Apply pattern initialization
            only when have_insn_for return true for the mode. Fix a memory leak.
    
    gcc/testsuite/ChangeLog:
    
    2021-11-10  qing zhao  <qing.zhao@oracle.com>
    
            * gcc.target/i386/auto-init-6.c: _Complex long double is initialized
            to zero now with -ftrivial-auto-var-init=pattern.

Diff:
---
 gcc/internal-fn.c                           | 14 ++++++++------
 gcc/testsuite/gcc.target/i386/auto-init-6.c |  6 ++++--
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/gcc/internal-fn.c b/gcc/internal-fn.c
index 0cba95411a6..e8fd16b9c21 100644
--- a/gcc/internal-fn.c
+++ b/gcc/internal-fn.c
@@ -3059,10 +3059,10 @@ expand_DEFERRED_INIT (internal_fn, gcall *stmt)
       mark_addressable (lhs);
       tree var_addr = build_fold_addr_expr (lhs);
 
-      tree value = (init_type == AUTO_INIT_PATTERN) ?
-		    build_int_cst (integer_type_node,
-				   INIT_PATTERN_VALUE) :
-		    integer_zero_node;
+      tree value = (init_type == AUTO_INIT_PATTERN)
+		    ? build_int_cst (integer_type_node,
+				     INIT_PATTERN_VALUE)
+		    : integer_zero_node;
       tree m_call = build_call_expr (builtin_decl_implicit (BUILT_IN_MEMSET),
 				     3, var_addr, value, var_size);
       /* Expand this memset call.  */
@@ -3073,15 +3073,17 @@ expand_DEFERRED_INIT (internal_fn, gcall *stmt)
       /* If this variable is in a register use expand_assignment.
 	 For boolean scalars force zero-init.  */
       tree init;
+      scalar_int_mode var_mode;
       if (TREE_CODE (TREE_TYPE (lhs)) != BOOLEAN_TYPE
 	  && tree_fits_uhwi_p (var_size)
 	  && (init_type == AUTO_INIT_PATTERN
 	      || !is_gimple_reg_type (var_type))
 	  && int_mode_for_size (tree_to_uhwi (var_size) * BITS_PER_UNIT,
-				0).exists ())
+				0).exists (&var_mode)
+	  && have_insn_for (SET, var_mode))
 	{
 	  unsigned HOST_WIDE_INT total_bytes = tree_to_uhwi (var_size);
-	  unsigned char *buf = (unsigned char *) xmalloc (total_bytes);
+	  unsigned char *buf = XALLOCAVEC (unsigned char, total_bytes);
 	  memset (buf, (init_type == AUTO_INIT_PATTERN
 			? INIT_PATTERN_VALUE : 0), total_bytes);
 	  tree itype = build_nonstandard_integer_type
diff --git a/gcc/testsuite/gcc.target/i386/auto-init-6.c b/gcc/testsuite/gcc.target/i386/auto-init-6.c
index 339f8bc2966..e53385f0eb7 100644
--- a/gcc/testsuite/gcc.target/i386/auto-init-6.c
+++ b/gcc/testsuite/gcc.target/i386/auto-init-6.c
@@ -1,4 +1,6 @@
 /* Verify pattern initialization for complex type automatic variables.  */
+/* Note, _Complex long double is initialized to zeroes due to the current
+   implemenation limitation.  */
 /* { dg-do compile } */
 /* { dg-options "-ftrivial-auto-var-init=pattern -march=x86-64 -mtune=generic -msse" } */
 
@@ -15,6 +17,6 @@ _Complex long double foo()
   return result;
 }
 
-/* { dg-final { scan-assembler-times "long\t-16843010" 10  { target { ! ia32 } } } } */
-/* { dg-final { scan-assembler-times "long\t-16843010" 6  { target { ia32 } } } } */
+/* { dg-final { scan-assembler-times "long\t0" 8  { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler-times "long\t-16843010" 6  } } */