From 1be1148d797dbb24fc866a9f9a98c85085db10c4 Mon Sep 17 00:00:00 2001 From: Richard Sandiford Date: Thu, 30 Mar 2023 11:09:08 +0100 Subject: [PATCH] aarch64: Tweak priorities of parsing-related errors There are three main kinds of error reported during parsing, in increasing order of priority: - AARCH64_OPDE_RECOVERABLE (register seen instead of immediate) - AARCH64_OPDE_SYNTAX_ERROR - AARCH64_OPDE_FATAL_SYNTAX_ERROR This priority makes sense when comparing errors reported against the same operand. But if we get to operand 3 (say) and see a register instead of an immediate, that's likely to be a better match than something that fails with a syntax error at operand 1. The idea of this patch is to prioritise parsing-related errors based on operand index first, then by error code. Post-parsing errors still win over parsing errors, and their relative priorities don't change. --- gas/config/tc-aarch64.c | 50 ++++++++++++++++++++--- gas/testsuite/gas/aarch64/sme-8-illegal.l | 12 +++--- 2 files changed, 51 insertions(+), 11 deletions(-) diff --git a/gas/config/tc-aarch64.c b/gas/config/tc-aarch64.c index 1851f83ad05..c8e37623d9e 100644 --- a/gas/config/tc-aarch64.c +++ b/gas/config/tc-aarch64.c @@ -5769,6 +5769,44 @@ output_operand_error_record (const operand_error_record *record, char *str) } } +/* Return true if the presence of error A against an instruction means + that error B should not be reported. This is only used as a first pass, + to pick the kind of error that we should report. */ + +static bool +better_error_p (operand_error_record *a, operand_error_record *b) +{ + /* For errors reported during parsing, prefer errors that relate to + later operands, since that implies that the earlier operands were + syntactically valid. + + For example, if we see a register R instead of an immediate in + operand N, we'll report that as a recoverable "immediate operand + required" error. This is because there is often another opcode + entry that accepts a register operand N, and any errors about R + should be reported against the register forms of the instruction. + But if no such register form exists, the recoverable error should + still win over a syntax error against operand N-1. + + For these purposes, count an error reported at the end of the + assembly string as equivalent to an error reported against the + final operand. This means that opcode entries that expect more + operands win over "unexpected characters following instruction". */ + if (a->detail.kind <= AARCH64_OPDE_FATAL_SYNTAX_ERROR + && b->detail.kind <= AARCH64_OPDE_FATAL_SYNTAX_ERROR) + { + int a_index = (a->detail.index < 0 + ? aarch64_num_of_operands (a->opcode) - 1 + : a->detail.index); + int b_index = (b->detail.index < 0 + ? aarch64_num_of_operands (b->opcode) - 1 + : b->detail.index); + if (a_index != b_index) + return a_index > b_index; + } + return operand_error_higher_severity_p (a->detail.kind, b->detail.kind); +} + /* Process and output the error message about the operand mismatching. When this function is called, the operand error information had @@ -5787,7 +5825,7 @@ output_operand_error_report (char *str, bool non_fatal_only) enum aarch64_operand_error_kind kind; operand_error_record *curr; operand_error_record *head = operand_error_report.head; - operand_error_record *record = NULL; + operand_error_record *record; /* No error to report. */ if (head == NULL) @@ -5811,7 +5849,7 @@ output_operand_error_report (char *str, bool non_fatal_only) /* Find the error kind of the highest severity. */ DEBUG_TRACE ("multiple opcode entries with error kind"); - kind = AARCH64_OPDE_NIL; + record = NULL; for (curr = head; curr != NULL; curr = curr->next) { gas_assert (curr->detail.kind != AARCH64_OPDE_NIL); @@ -5832,14 +5870,16 @@ output_operand_error_report (char *str, bool non_fatal_only) { DEBUG_TRACE ("\t%s", operand_mismatch_kind_names[curr->detail.kind]); } - if (operand_error_higher_severity_p (curr->detail.kind, kind) - && (!non_fatal_only || (non_fatal_only && curr->detail.non_fatal))) - kind = curr->detail.kind; + if ((!non_fatal_only || curr->detail.non_fatal) + && (!record || better_error_p (curr, record))) + record = curr; } + kind = (record ? record->detail.kind : AARCH64_OPDE_NIL); gas_assert (kind != AARCH64_OPDE_NIL || non_fatal_only); /* Pick up one of errors of KIND to report. */ + record = NULL; for (curr = head; curr != NULL; curr = curr->next) { /* If we don't want to print non-fatal errors then don't consider them diff --git a/gas/testsuite/gas/aarch64/sme-8-illegal.l b/gas/testsuite/gas/aarch64/sme-8-illegal.l index ee9f76f3b9c..7123e8d9eac 100644 --- a/gas/testsuite/gas/aarch64/sme-8-illegal.l +++ b/gas/testsuite/gas/aarch64/sme-8-illegal.l @@ -1,7 +1,7 @@ [^:]*: Assembler messages: -[^:]*:[0-9]+: Error: unexpected characters following instruction -- `smstart x0' -[^:]*:[0-9]+: Error: unexpected characters following instruction -- `smstart sa' -[^:]*:[0-9]+: Error: unexpected characters following instruction -- `smstart zm' -[^:]*:[0-9]+: Error: unexpected characters following instruction -- `smstop x0' -[^:]*:[0-9]+: Error: unexpected characters following instruction -- `smstop sa' -[^:]*:[0-9]+: Error: unexpected characters following instruction -- `smstop zm' +[^:]*:[0-9]+: Error: unknown or missing PSTATE field name at operand 1 -- `smstart x0' +[^:]*:[0-9]+: Error: unknown or missing PSTATE field name at operand 1 -- `smstart sa' +[^:]*:[0-9]+: Error: unknown or missing PSTATE field name at operand 1 -- `smstart zm' +[^:]*:[0-9]+: Error: unknown or missing PSTATE field name at operand 1 -- `smstop x0' +[^:]*:[0-9]+: Error: unknown or missing PSTATE field name at operand 1 -- `smstop sa' +[^:]*:[0-9]+: Error: unknown or missing PSTATE field name at operand 1 -- `smstop zm' -- 2.30.2