Restore INDIRECT_REF asm operand heuristic with MEM_REF

As noticed we are looking for INDIRECT_REF with allows_mem to avoid
a copy since then we're sure the operand is in memory (assuming
*& is folded).  But INDIRECT_REFs are no longer a thing, the following
replaces the check with a check for a MEM_REF with a non-ADDR_EXPR
operand.  This should fix the regression part without fully
exploring all possibilities around tcc_reference operands.

I've placed an assert that we do not see an INDIRECT_REF here.
While we gimplify asm operands we never do any checking on its
IL afterwards.

2022-03-09  Richard Biener  <rguenther@suse.de>

	* cfgexpand.cc (expand_gimple_asm): Special-case MEM_REF
	with non-decl operand, avoiding a copy.

diff --git a/gcc/cfgexpand.cc b/gcc/cfgexpand.cc
index 4f99f04..d3cc77d 100644 (file)
--- a/gcc/cfgexpand.cc
+++ b/gcc/cfgexpand.cc
@@ -3290,7 +3290,10 @@ expand_asm_stmt (gasm *stmt)
 
       generating_concat_p = 0;
 
-      if ((TREE_CODE (val) == INDIRECT_REF && allows_mem)
+      gcc_assert (TREE_CODE (val) != INDIRECT_REF);
+      if (((TREE_CODE (val) == MEM_REF
+           && TREE_CODE (TREE_OPERAND (val, 0)) != ADDR_EXPR)
+          && allows_mem)
          || (DECL_P (val)
              && (allows_mem || REG_P (DECL_RTL (val)))
              && ! (REG_P (DECL_RTL (val))