middle-end/104644 - recursion with bswap match.pd pattern
The following patch avoids infinite recursion during generic folding. The (cmp (bswap @0) INTEGER_CST@1) simplification relies on (bswap @1) actually being simplified, if it is not simplified, we just move the bswap from one operand to the other and if @0 is also INTEGER_CST, we apply the same rule next. The reason why bswap @1 isn't folded to INTEGER_CST is that the INTEGER_CST has TREE_OVERFLOW set on it and fold-const-call.cc predicate punts in such cases: static inline bool integer_cst_p (tree t) { return TREE_CODE (t) == INTEGER_CST && !TREE_OVERFLOW (t); } The patch uses ! modifier to ensure the bswap is simplified and extends support to GENERIC by means of requiring !EXPR_P which is not perfect but a conservative approximation. 2022-02-22 Richard Biener <rguenther@suse.de> PR tree-optimization/104644 * doc/match-and-simplify.texi: Amend ! documentation. * genmatch.cc (expr::gen_transform): Code-generate ! support for GENERIC. (parser::parse_expr): Allow ! for GENERIC. * match.pd (cmp (bswap @0) INTEGER_CST@1): Use ! modifier on bswap. * gcc.dg/pr104644.c: New test. Co-Authored-by: Jakub Jelinek <jakub@redhat.com>
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@ -374,8 +374,10 @@ for example
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which moves the outer @code{plus} operation to the inner arms
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which moves the outer @code{plus} operation to the inner arms
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of the @code{vec_cond} expression but only if the actual plus
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of the @code{vec_cond} expression but only if the actual plus
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operations both simplify. Note this is currently only supported
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operations both simplify. Note that on @code{GENERIC} a simple
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for code generation targeting @code{GIMPLE}.
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operand means that the result satisfies @code{!EXPR_P} which
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can be limiting if the operation itself simplifies but the
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remaining operand is an (unrelated) expression.
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As intermediate conversions are often optional there is a way to
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As intermediate conversions are often optional there is a way to
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avoid the need to repeat patterns both with and without such
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avoid the need to repeat patterns both with and without such
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@ -2553,19 +2553,20 @@ expr::gen_transform (FILE *f, int indent, const char *dest, bool gimple,
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fprintf_indent (f, indent, "_r%d = fold_build%d_loc (loc, %s, %s",
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fprintf_indent (f, indent, "_r%d = fold_build%d_loc (loc, %s, %s",
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depth, ops.length(), opr_name, type);
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depth, ops.length(), opr_name, type);
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else
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else
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{
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fprintf_indent (f, indent, "_r%d = maybe_build_call_expr_loc (loc, "
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fprintf_indent (f, indent, "{\n");
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"%s, %s, %d", depth, opr_name, type, ops.length());
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fprintf_indent (f, indent, " _r%d = maybe_build_call_expr_loc (loc, "
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"%s, %s, %d", depth, opr_name, type, ops.length());
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}
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for (unsigned i = 0; i < ops.length (); ++i)
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for (unsigned i = 0; i < ops.length (); ++i)
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fprintf (f, ", _o%d[%u]", depth, i);
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fprintf (f, ", _o%d[%u]", depth, i);
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fprintf (f, ");\n");
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fprintf (f, ");\n");
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if (opr->kind != id_base::CODE)
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if (opr->kind != id_base::CODE)
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{
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{
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fprintf_indent (f, indent, " if (!_r%d)\n", depth);
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fprintf_indent (f, indent, "if (!_r%d)\n", depth);
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fprintf_indent (f, indent, " goto %s;\n", fail_label);
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fprintf_indent (f, indent, " goto %s;\n", fail_label);
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fprintf_indent (f, indent, "}\n");
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}
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if (force_leaf)
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{
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fprintf_indent (f, indent, "if (EXPR_P (_r%d))\n", depth);
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fprintf_indent (f, indent, " goto %s;\n", fail_label);
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}
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}
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if (*opr == CONVERT_EXPR)
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if (*opr == CONVERT_EXPR)
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{
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{
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@ -4297,9 +4298,6 @@ parser::parse_expr ()
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&& token->type == CPP_NOT
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&& token->type == CPP_NOT
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&& !(token->flags & PREV_WHITE))
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&& !(token->flags & PREV_WHITE))
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{
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{
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if (!gimple)
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fatal_at (token, "forcing simplification to a leaf is not supported "
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"for GENERIC");
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eat_token (CPP_NOT);
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eat_token (CPP_NOT);
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e->force_leaf = true;
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e->force_leaf = true;
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}
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}
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@ -3962,7 +3962,7 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
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(simplify
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(simplify
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(cmp (bswap @0) INTEGER_CST@1)
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(cmp (bswap @0) INTEGER_CST@1)
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(with { tree ctype = TREE_TYPE (@1); }
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(with { tree ctype = TREE_TYPE (@1); }
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(cmp (convert:ctype @0) (bswap @1)))))
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(cmp (convert:ctype @0) (bswap! @1)))))
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/* (bswap(x) >> C1) & C2 can sometimes be simplified to (x >> C3) & C2. */
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/* (bswap(x) >> C1) & C2 can sometimes be simplified to (x >> C3) & C2. */
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(simplify
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(simplify
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(bit_and (convert1? (rshift@0 (convert2? (bswap@4 @1)) INTEGER_CST@2))
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(bit_and (convert1? (rshift@0 (convert2? (bswap@4 @1)) INTEGER_CST@2))
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@ -0,0 +1,9 @@
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/* PR tree-optimization/104644 */
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/* { dg-do compile } */
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/* { dg-options "-Wno-overflow" } */
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int
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foo (void)
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{
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return __builtin_bswap16 (1.31072e+5f) != (signed char) 1.31072e+5f;
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}
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