From 8e39410125a81af00fac28f186e8e3e00f5751e3 Mon Sep 17 00:00:00 2001 From: Jan Hubicka Date: Fri, 20 Nov 2020 11:06:48 +0100 Subject: [PATCH] Fix comparsion of {CLOBBER} in icf after fixing few issues I gotto stage where 1.4M icf mismatches are due to comparing two gimple clobber. The problem is that operand_equal_p match clobber case CONSTRUCTOR: /* In GIMPLE empty constructors are allowed in initializers of aggregates. */ return !CONSTRUCTOR_NELTS (arg0) && !CONSTRUCTOR_NELTS (arg1); But this happens too late after comparing its types (that are not very relevant for memory store). In the context of ipa-icf we do not really need to match RHS of gimple clobbers: it is enough to know that the LHS stores can be considered equivalent. I this added logic to hash them all the same way and compare using TREE_CLOBBER_P flag. I see other option in extending operand_equal_p in fold-const to handle them more generously or making stmt hash and compare to skip comparing/hashing RHS of gimple_clobber_p. * ipa-icf-gimple.c (func_checker::hash_operand): Hash gimple clobber. (func_checker::operand_equal_p): Special case gimple clobber. --- gcc/ipa-icf-gimple.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/gcc/ipa-icf-gimple.c b/gcc/ipa-icf-gimple.c index ffb1baddbdb..69bc9ab5b34 100644 --- a/gcc/ipa-icf-gimple.c +++ b/gcc/ipa-icf-gimple.c @@ -245,6 +245,14 @@ func_checker::hash_operand (const_tree arg, inchash::hash &hstate, break; } + /* In gimple all clobbers can be considered equal: while comparaing two + gimple clobbers we match the left hand memory accesses. */ + if (TREE_CLOBBER_P (arg)) + { + hstate.add_int (0xc10bbe5); + return; + } + return operand_compare::hash_operand (arg, hstate, flags); } @@ -306,6 +314,10 @@ func_checker::operand_equal_p (const_tree t1, const_tree t2, default: break; } + /* In gimple all clobbers can be considered equal. We match the right hand + memory accesses. */ + if (TREE_CLOBBER_P (t1) || TREE_CLOBBER_P (t2)) + return TREE_CLOBBER_P (t1) == TREE_CLOBBER_P (t2); return operand_compare::operand_equal_p (t1, t2, flags); } -- 2.30.2