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From: Richard Biener <rguenth@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r14-285] tree-optimization/109594 - wrong register promotion Date: Thu, 27 Apr 2023 08:38:04 +0000 (GMT) [thread overview] Message-ID: <20230427083804.B0A953858C27@sourceware.org> (raw) https://gcc.gnu.org/g:7bcdcf86e8272eeb524cc1dcb0ada8c8cfe6f27e commit r14-285-g7bcdcf86e8272eeb524cc1dcb0ada8c8cfe6f27e Author: Richard Biener <rguenther@suse.de> Date: Mon Apr 24 13:20:25 2023 +0200 tree-optimization/109594 - wrong register promotion We fail to verify the constraints under which we allow handled components to wrap registers. The gcc.dg/pr70022.c testcase shows that we happily end up with _2 = VIEW_CONVERT_EXPR<int[4]>(v_1(D)) as produced by SSA rewrite and update_address_taken. But the intent was that we wrap registers with at most a single level of handled components and specifically only allow __real, __imag, BIT_FIELD_REF and VIEW_CONVERT_EXPR on them, but not ARRAY_REF or COMPONENT_REF. Together with the improved gimple_load predicate taking advantage of the above and ASAN this eventually ICEd. The following fixes update_address_taken as to this constraint. PR tree-optimization/109594 * tree-ssa.cc (non_rewritable_mem_ref_base): Constrain what we rewrite to a register based on the above. Diff: --- gcc/tree-ssa.cc | 35 ++++++++++++++++++++++++++++------- 1 file changed, 28 insertions(+), 7 deletions(-) diff --git a/gcc/tree-ssa.cc b/gcc/tree-ssa.cc index 4ca1f5f3104..70828355c2b 100644 --- a/gcc/tree-ssa.cc +++ b/gcc/tree-ssa.cc @@ -1572,14 +1572,30 @@ non_rewritable_mem_ref_base (tree ref) if (DECL_P (ref)) return NULL_TREE; - if (! (base = CONST_CAST_TREE (strip_invariant_refs (ref)))) + switch (TREE_CODE (ref)) { - base = get_base_address (ref); - if (DECL_P (base)) - return base; - return NULL_TREE; + case REALPART_EXPR: + case IMAGPART_EXPR: + case BIT_FIELD_REF: + if (DECL_P (TREE_OPERAND (ref, 0))) + return NULL_TREE; + break; + case VIEW_CONVERT_EXPR: + if (DECL_P (TREE_OPERAND (ref, 0))) + { + if (TYPE_SIZE (TREE_TYPE (ref)) + != TYPE_SIZE (TREE_TYPE (TREE_OPERAND (ref, 0)))) + return TREE_OPERAND (ref, 0); + return NULL_TREE; + } + break; + /* We would need to rewrite ARRAY_REFs or COMPONENT_REFs and even + more so multiple levels of handled components. */ + default:; } + base = ref; + /* But watch out for MEM_REFs we cannot lower to a VIEW_CONVERT_EXPR or a BIT_FIELD_REF. */ if (TREE_CODE (base) == MEM_REF @@ -1630,9 +1646,14 @@ non_rewritable_mem_ref_base (tree ref) return decl; } + /* We cannot rewrite a decl in the base. */ + base = get_base_address (ref); + if (DECL_P (base)) + return base; + /* We cannot rewrite TARGET_MEM_REFs. */ - if (TREE_CODE (base) == TARGET_MEM_REF - && TREE_CODE (TREE_OPERAND (base, 0)) == ADDR_EXPR) + else if (TREE_CODE (base) == TARGET_MEM_REF + && TREE_CODE (TREE_OPERAND (base, 0)) == ADDR_EXPR) { tree decl = TREE_OPERAND (TREE_OPERAND (base, 0), 0); if (! DECL_P (decl))
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