If the compiler is configured with --with-fpu=<!auto> (or invoked
with, say, -mfpu=neon), then specifying -mcpu=neoverse-n1 can lead to
an unexpected warning: cc1: warning: switch ‘-mcpu=neoverse-n1’
conflicts with ‘-march=armv8.2-a’ switch
The fix for this is to correctly remove all the feature bits relating
to simd/fp units when -mfpu is used, not just those bits that form
part of the -mfpu specification (which is a subset).
gcc:
PR target/100067
* config/arm/arm.c (arm_configure_build_target): Strip
isa_all_fpbits
from the isa_delta when -mfpu has been used.
(arm_options_perform_arch_sanity_checks): It's the architecture
that
lacks an FPU not the processor.
---
gcc/config/arm/arm.c | 25 ++++++++++++++-----------
1 file changed, 14 insertions(+), 11 deletions(-)
diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index 8910dad8214..475fb0d827f 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -3230,21 +3230,22 @@ arm_configure_build_target (struct arm_build_target *target,
bitmap_xor (isa_delta, cpu_isa, target->isa);
/* Ignore any bits that are quirk bits. */
bitmap_and_compl (isa_delta, isa_delta, isa_quirkbits);
- /* Ignore (for now) any bits that might be set by -mfpu. */
- bitmap_and_compl (isa_delta, isa_delta, isa_all_fpubits_internal);
-
- /* And if the target ISA lacks floating point, ignore any
- extensions that depend on that. */
- if (!bitmap_bit_p (target->isa, isa_bit_vfpv2))
+ /* If the user (or the default configuration) has specified a
+ specific FPU, then ignore any bits that depend on the FPU
+ configuration. Do similarly if using the soft-float
+ ABI. */
+ if (opts->x_arm_fpu_index != TARGET_FPU_auto
+ || arm_float_abi == ARM_FLOAT_ABI_SOFT)
bitmap_and_compl (isa_delta, isa_delta, isa_all_fpbits);
if (!bitmap_empty_p (isa_delta))
{
if (warn_compatible)
warning (0, "switch %<-mcpu=%s%> conflicts "
- "with %<-march=%s%> switch",
- arm_selected_cpu->common.name,
- arm_selected_arch->common.name);
+ "with switch %<-march=%s%>",
+ opts->x_arm_cpu_string,
+ opts->x_arm_arch_string);
+
/* -march wins for code generation.
-mcpu wins for default tuning. */
if (!arm_selected_tune)
@@ -3395,7 +3396,9 @@ arm_configure_build_target (struct arm_build_target *target,
auto_sbitmap fpu_bits (isa_num_bits);
arm_initialize_isa (fpu_bits, arm_selected_fpu->isa_bits);
- bitmap_and_compl (target->isa, target->isa, isa_all_fpubits_internal);
+ /* Clear out ALL bits relating to the FPU/simd extensions, to avoid
+ potentially invalid combinations later on that we can't match. */
+ bitmap_and_compl (target->isa, target->isa, isa_all_fpbits);
bitmap_ior (target->isa, target->isa, fpu_bits);
}
@@ -3856,7 +3859,7 @@ arm_options_perform_arch_sanity_checks (void)
arm_pcs_default = ARM_PCS_AAPCS_VFP;
if (!bitmap_bit_p (arm_active_target.isa, isa_bit_vfpv2)
&& !bitmap_bit_p (arm_active_target.isa, isa_bit_mve))
- error ("%<-mfloat-abi=hard%>: selected processor lacks an FPU");
+ error ("%<-mfloat-abi=hard%>: selected architecture lacks an FPU");
}
else
arm_pcs_default = ARM_PCS_AAPCS;
