Hi, On Thu, Jul 21, 2011 at 11:40:32AM +0200, Martin Jambor wrote: > Hi, > > On Thu, Jul 21, 2011 at 10:34:35AM +0200, Richard Guenther wrote: > > On Wed, 20 Jul 2011, Ulrich Weigand wrote: > > > > > Richard Guenther wrote: > > > > On Tue, Jul 19, 2011 at 8:20 PM, Ulrich Weigand <uweig...@de.ibm.com> > > > > wrote: > > > > > The problem is that in this expression > > > > > disappear = VIEW_CONVERT_EXPR<struct VecClass>(x_8); > > > > > the rhs is considered unaligned and blocks the SRA transformation. > > > > > > > > > > The check you added for SSA_NAMEs doesn't hit, because the SSA_NAME is > > > > > encapsulated in a VIEW_CONVERT_EXPR. When get_object_alignment is > > > > > called, > > > > > the VIEW_CONVERT_EXPR is stripped off by get_inner_reference and the > > > > > SSA_NAME appears, but then get_object_alignment doesn't handle it > > > > > and just returns the default alignment of 8 bits. > > > > > > > > > > Maybe get_object_alignment should itself handle SSA_NAMEs? > > > > > > > > But what should it return for a rvalue? There is no "alignment" here. > > > > I think SRA should avoid asking for rvalues. > > > > > > I must admit I do not fully understand what the SRA code is attempting > > > to achieve here ... Could you elaborate on what you mean by "avoid > > > asking for rvalues"? Should the SRA code never check the RHS of an > > > assignment for alignment, only the LHS? Or should it classify the RHS > > > tree according to whether the access is rvalue or lvalue (how would > > > that work?)? > > > > Well, it should only ask for stores / loads. I'm not sure what we'd > > want to return as alignment for an rvalue - MAX_ALIGNMENT? What should > > we return for get_object_alignment of an INTEGER_CST for example? > > > > Yeah, we certainly should not be examining alingment of invariants and > of conversions of ssa names in. As far as rvalues in general are > concerned, I don't really know which gimple predicate that would be. > A comment suggests is_gimple_val but that does not return true for a > VIEW_CONVERT_EXPR of an SSA_NAME and would return true for aggregate > variables (which perhaps would not be a problem, however they do have > an alignment). > > So at the moment I'd go for stripping all conversions from exp before > the first if in tree_non_mode_aligned_mem_p and adding > is_gimple_min_invariant to the condition. Does that make sense?
Like this? Ulrich, can you please verify it works? I have bootstrapped this on x86_64 but there it obvioulsy works and my run of compile/testsuite on compile farm sparc64 will take some time (plus, the testcase you complained about passes there). Thanks, Martin 2011-07-25 Martin Jambor <mjam...@suse.cz> * tree-sra.c (tree_non_mode_aligned_mem_p): Strip conversions and return false for invariants. Index: src/gcc/tree-sra.c =================================================================== --- src.orig/gcc/tree-sra.c +++ src/gcc/tree-sra.c @@ -1075,9 +1075,14 @@ tree_non_mode_aligned_mem_p (tree exp) enum machine_mode mode = TYPE_MODE (TREE_TYPE (exp)); unsigned int align; + while (CONVERT_EXPR_P (exp) + || TREE_CODE (exp) == VIEW_CONVERT_EXPR) + exp = TREE_OPERAND (exp, 0); + if (TREE_CODE (exp) == SSA_NAME || TREE_CODE (exp) == MEM_REF || mode == BLKmode + || is_gimple_min_invariant (exp) || !STRICT_ALIGNMENT) return false;