[gcc r14-4714] middle-end: ifcvt: Allow any const IFN in conditional blocks

[gcc r14-4714] middle-end: ifcvt: Allow any const IFN in conditional blocks

[Tamar Christina]

https://gcc.gnu.org/g:b0fe8f2f960d746e61debd61655f231f503bccaa

commit r14-4714-gb0fe8f2f960d746e61debd61655f231f503bccaa
Author: Tamar Christina <tamar.christina@arm.com>
Date:   Wed Oct 18 09:33:30 2023 +0100

    middle-end: ifcvt: Allow any const IFN in conditional blocks
    
    When ifcvt was initially added masking was not a thing and as such it was
    rather conservative in what it supported.
    
    For builtins it only allowed C99 builtin functions which it knew it can fold
    away.
    
    These days the vectorizer is able to deal with needing to mask IFNs itself.
    vectorizable_call is able vectorize the IFN by emitting a VEC_PERM_EXPR after
    the operation to emulate the masking.
    
    This is then used by match.pd to conver the IFN into a masked variant if it's
    available.
    
    For these reasons the restriction in ifconvert is no longer require and we
    needless block vectorization when we can effectively handle the operations.
    
    Bootstrapped Regtested on aarch64-none-linux-gnu and no issues.
    
    Note: This patch is part of a testseries and tests for it are added in the
    AArch64 patch that adds supports for the optab.
    
    gcc/ChangeLog:
    
            PR tree-optimization/109154
            * tree-if-conv.cc (if_convertible_stmt_p): Allow any const IFN.

Diff:
---
 gcc/tree-if-conv.cc | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/gcc/tree-if-conv.cc b/gcc/tree-if-conv.cc
index 3b4238831c3e..edce842db940 100644
--- a/gcc/tree-if-conv.cc
+++ b/gcc/tree-if-conv.cc
@@ -1107,17 +1107,21 @@ if_convertible_stmt_p (gimple *stmt, vec<data_reference_p> refs)
 
     case GIMPLE_CALL:
       {
+	/* There are some IFN_s that are used to replace builtins but have the
+	   same semantics.  Even if MASK_CALL cannot handle them vectorable_call
+	   will insert the proper selection, so do not block conversion.  */
+	int flags = gimple_call_flags (stmt);
+	if ((flags & ECF_CONST)
+	    && !(flags & ECF_LOOPING_CONST_OR_PURE)
+	    && gimple_call_combined_fn (stmt) != CFN_LAST)
+	  return true;
+
 	tree fndecl = gimple_call_fndecl (stmt);
 	if (fndecl)
 	  {
 	    /* We can vectorize some builtins and functions with SIMD
 	       "inbranch" clones.  */
-	    int flags = gimple_call_flags (stmt);
 	    struct cgraph_node *node = cgraph_node::get (fndecl);
-	    if ((flags & ECF_CONST)
-		&& !(flags & ECF_LOOPING_CONST_OR_PURE)
-		&& fndecl_built_in_p (fndecl))
-	      return true;
 	    if (node && node->simd_clones != NULL)
 	      /* Ensure that at least one clone can be "inbranch".  */
 	      for (struct cgraph_node *n = node->simd_clones; n != NULL;
@@ -1129,6 +1133,7 @@ if_convertible_stmt_p (gimple *stmt, vec<data_reference_p> refs)
 		    return true;
 		  }
 	  }
+
 	return false;
       }