From 54bab2816dfd025fc53618e46be140573d5bc02e Mon Sep 17 00:00:00 2001 From: Thomas Preud'homme Date: Wed, 21 Jun 2017 14:57:53 +0100 Subject: [PATCH] [ARM] Rework selection of feature bits to base build attributes on === Context === This patch is part of a patch series to add support for ARMv8-R architecture. Its purpose is to set the feature bits on which to decide what the build attributes should be according to the mode (autodetection, user specified architecture or CPU, or -march/-mcpu=all). === Motivation === Currently, the flags variable which is used to determine the build attribute is constructed from the instruction used (arm_arch_used and thumb_arch_used) as well as the user specified architecture or CPU (selected_cpu). This means when several .arch are specified the resulting feature bits can be such that no architecture provide them all and can thus result in incorrect Tag_CPU_arch. See for instance what having both .arch armv8-a and .arch armv8-m.base would result in. This is not caught by the testsuite because of further bugs in the Tag_CPU_arch build attribute value selection logic (see next patch in the series). === Patch description === As one would expect, this patch solves the problem by setting flags from feature bits used if in autodetection mode [1] and from selected_cpu otherwise. The logic to set arm_ext_v1, arm_ext_v4t and arm_ext_os feature bits is also moved to only run in autodetection mode since otherwise the architecture or CPU would have a consistent set of feature bits already. [1] No architecture or CPU was specified by the user 2017-06-21 Thomas Preud'homme gas/ * config/tc-arm.c (aeabi_set_public_attributes): Populate flags from feature bits used or selected_cpu depending on whether a CPU was selected by the user. --- gas/ChangeLog | 6 ++++++ gas/config/tc-arm.c | 40 ++++++++++++++++++++++++---------------- 2 files changed, 30 insertions(+), 16 deletions(-) diff --git a/gas/ChangeLog b/gas/ChangeLog index 4c8fc41..82b25ac 100644 --- a/gas/ChangeLog +++ b/gas/ChangeLog @@ -1,5 +1,11 @@ 2017-06-21 Thomas Preud'homme + * config/tc-arm.c (aeabi_set_public_attributes): Populate flags from + feature bits used or selected_cpu depending on whether a CPU was + selected by the user. + +2017-06-21 Thomas Preud'homme + * config/tc-arm.c (aeabi_set_public_attributes): Test *mcpu_ext_opt to decide whether to set Tag_DSP_extension build attribute value. Remove now useless arm_arch variable. diff --git a/gas/config/tc-arm.c b/gas/config/tc-arm.c index 88f3dc9..86acb86 100644 --- a/gas/config/tc-arm.c +++ b/gas/config/tc-arm.c @@ -26605,19 +26605,33 @@ aeabi_set_public_attributes (void) arm_feature_set arm_arch_v8m_base = ARM_ARCH_V8M_BASE; const cpu_arch_ver_table *p; - /* Choose the architecture based on the capabilities of the requested cpu - (if any) and/or the instructions actually used. */ - ARM_MERGE_FEATURE_SETS (flags, arm_arch_used, thumb_arch_used); - ARM_MERGE_FEATURE_SETS (flags, flags, *mfpu_opt); - ARM_MERGE_FEATURE_SETS (flags, flags, selected_cpu); + /* Autodetection mode, choose the architecture based the instructions + actually used. */ + if (no_cpu_selected ()) + { + ARM_MERGE_FEATURE_SETS (flags, arm_arch_used, thumb_arch_used); - if (ARM_CPU_HAS_FEATURE (arm_arch_used, arm_arch_any)) - ARM_MERGE_FEATURE_SETS (flags, flags, arm_ext_v1); + if (ARM_CPU_HAS_FEATURE (arm_arch_used, arm_arch_any)) + ARM_MERGE_FEATURE_SETS (flags, flags, arm_ext_v1); - if (ARM_CPU_HAS_FEATURE (thumb_arch_used, arm_arch_any)) - ARM_MERGE_FEATURE_SETS (flags, flags, arm_ext_v4t); + if (ARM_CPU_HAS_FEATURE (thumb_arch_used, arm_arch_any)) + ARM_MERGE_FEATURE_SETS (flags, flags, arm_ext_v4t); - selected_cpu = flags; + /* We need to make sure that the attributes do not identify us as v6S-M + when the only v6S-M feature in use is the Operating System + Extensions. */ + if (ARM_CPU_HAS_FEATURE (flags, arm_ext_os)) + if (!ARM_CPU_HAS_FEATURE (flags, arm_arch_v6m_only)) + ARM_CLEAR_FEATURE (flags, flags, arm_ext_os); + + /* Code run during relaxation relies on selected_cpu being set. */ + selected_cpu = flags; + } + /* Otherwise, choose the architecture based on the capabilities of the + requested cpu. */ + else + flags = selected_cpu; + ARM_MERGE_FEATURE_SETS (flags, flags, *mfpu_opt); /* Allow the user to override the reported architecture. */ if (object_arch) @@ -26626,12 +26640,6 @@ aeabi_set_public_attributes (void) ARM_MERGE_FEATURE_SETS (flags, flags, *object_arch); } - /* We need to make sure that the attributes do not identify us as v6S-M - when the only v6S-M feature in use is the Operating System Extensions. */ - if (ARM_CPU_HAS_FEATURE (flags, arm_ext_os)) - if (!ARM_CPU_HAS_FEATURE (flags, arm_arch_v6m_only)) - ARM_CLEAR_FEATURE (flags, flags, arm_ext_os); - tmp = flags; arch = 0; for (p = cpu_arch_ver; p->val; p++) -- 2.7.4