[PATCH] Restore INDIRECT_REF asm operand heuristic with MEM_REF

[PATCH] Restore INDIRECT_REF asm operand heuristic with MEM_REF

[Richard Biener]

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.

Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.

OK if that succeeds?

Thanks,
Richard.

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

	* cfgexpand.c (expand_gimple_asm): Special-case MEM_REF
	with non-decl operand, avoiding a copy.
---
 gcc/cfgexpand.cc | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/gcc/cfgexpand.cc b/gcc/cfgexpand.cc
index 4f99f040450..d3cc77d2ca9 100644
--- 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))
-- 
2.34.1

Re: [PATCH] Restore INDIRECT_REF asm operand heuristic with MEM_REF

[Jakub Jelinek]

On Wed, Mar 09, 2022 at 03:21:53PM +0100, Richard Biener wrote:
> 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.
> 
> Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.
> 
> OK if that succeeds?
> 
> Thanks,
> Richard.
> 
> 2022-03-09  Richard Biener  <rguenther@suse.de>
> 
> 	* cfgexpand.c (expand_gimple_asm): Special-case MEM_REF
> 	with non-decl operand, avoiding a copy.

LGTM.

	Jakub