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new 6f0da60bd79 libs/libbuiltin/compiler-rt: skip unsupported Arm VFP
builtins asm
6f0da60bd79 is described below
commit 6f0da60bd798fe65ad9e4a0ec6339abc045d77e9
Author: Udit Jain <[email protected]>
AuthorDate: Fri Jul 24 05:31:18 2026 +0530
libs/libbuiltin/compiler-rt: skip unsupported Arm VFP builtins asm
The compiler-rt builtins build globs every arm/*.S source, but several of
those hand-written assembly files require FPU features the target may not
have. Upstream compiler-rt selects them conditionally; NuttX did not, so
BUILTIN_COMPILER_RT builds for single-precision-FPU Arm targets (e.g.
Cortex-M33, -mfpu=fpv5-sp-d16) failed to assemble with errors such as
"selected FPU does not support instruction -- vadd.f64".
Filter the source list to match the configured FPU, in both the Makefile
and CMake builds:
- chkstk.S / chkstk2.S are Windows/MinGW-only stack probes, always
dropped;
- with no hardware FPU (!CONFIG_ARCH_FPU) all arm/*vfp.S are dropped;
- with a single-precision FPU (!CONFIG_ARCH_DPFPU) the double-precision
*df*vfp.S routines are dropped.
Reproduced against compiler-rt 17.0.1 with arm-none-eabi-gcc 14.2 using the
Cortex-M33 single-precision flags: 18 of 86 arm/*.S files failed to assemble
(17 double-precision *df*vfp.S plus chkstk.S); after the filter all
remaining
68 files assemble cleanly.
Fixes: https://github.com/apache/nuttx/issues/17386
Generated-by: Claude (Anthropic)
Signed-off-by: Udit Jain <[email protected]>
---
libs/libbuiltin/compiler-rt/CMakeLists.txt | 39 ++++++++++++++++++++++++++++++
libs/libbuiltin/compiler-rt/Make.defs | 27 +++++++++++++++++++++
2 files changed, 66 insertions(+)
diff --git a/libs/libbuiltin/compiler-rt/CMakeLists.txt
b/libs/libbuiltin/compiler-rt/CMakeLists.txt
index d1fa3f444fc..81d3e6d4e01 100644
--- a/libs/libbuiltin/compiler-rt/CMakeLists.txt
+++ b/libs/libbuiltin/compiler-rt/CMakeLists.txt
@@ -114,6 +114,45 @@ if(CONFIG_BUILTIN_COMPILER_RT)
list(REMOVE_ITEM RT_BUILTINS_SRCS ${x86_80_BIT_SOURCES})
endif()
+ # The Arm builtins ship hand-written VFP assembly whose FPU requirements the
+ # globs above ignore, so assemble only the files the configured FPU supports
+ # (upstream compiler-rt selects them conditionally). chkstk.S and chkstk2.S
+ # are Windows/MinGW-only stack probes; every *vfp.S needs a hardware FPU; and
+ # the double-precision *df*vfp.S routines additionally need a
double-precision
+ # FPU. Without this, single-precision-FPU targets such as Cortex-M33
+ # (fpv5-sp-d16) fail with "selected FPU does not support instruction". See
+ # apache/nuttx#17386.
+ if(CONFIG_ARCH_ARM)
+ set(RT_BUILTINS_ARM_EXCLUDE ${BUILTINS_DIR}/arm/chkstk.S
+ ${BUILTINS_DIR}/arm/chkstk2.S)
+ if(NOT CONFIG_ARCH_FPU)
+ file(GLOB RT_BUILTINS_ARM_VFP ${BUILTINS_DIR}/arm/*vfp.S)
+ list(APPEND RT_BUILTINS_ARM_EXCLUDE ${RT_BUILTINS_ARM_VFP})
+ elseif(NOT CONFIG_ARCH_DPFPU)
+ list(
+ APPEND
+ RT_BUILTINS_ARM_EXCLUDE
+ ${BUILTINS_DIR}/arm/adddf3vfp.S
+ ${BUILTINS_DIR}/arm/divdf3vfp.S
+ ${BUILTINS_DIR}/arm/eqdf2vfp.S
+ ${BUILTINS_DIR}/arm/extendsfdf2vfp.S
+ ${BUILTINS_DIR}/arm/fixdfsivfp.S
+ ${BUILTINS_DIR}/arm/fixunsdfsivfp.S
+ ${BUILTINS_DIR}/arm/floatsidfvfp.S
+ ${BUILTINS_DIR}/arm/floatunssidfvfp.S
+ ${BUILTINS_DIR}/arm/gedf2vfp.S
+ ${BUILTINS_DIR}/arm/gtdf2vfp.S
+ ${BUILTINS_DIR}/arm/ledf2vfp.S
+ ${BUILTINS_DIR}/arm/ltdf2vfp.S
+ ${BUILTINS_DIR}/arm/muldf3vfp.S
+ ${BUILTINS_DIR}/arm/nedf2vfp.S
+ ${BUILTINS_DIR}/arm/subdf3vfp.S
+ ${BUILTINS_DIR}/arm/truncdfsf2vfp.S
+ ${BUILTINS_DIR}/arm/unorddf2vfp.S)
+ endif()
+ list(REMOVE_ITEM RT_BUILTINS_SRCS ${RT_BUILTINS_ARM_EXCLUDE})
+ endif()
+
if(NOT CONFIG_COVERAGE_NONE)
target_compile_options(rt.builtins PRIVATE -fno-profile-instr-generate
-fno-coverage-mapping)
diff --git a/libs/libbuiltin/compiler-rt/Make.defs
b/libs/libbuiltin/compiler-rt/Make.defs
index d5b66a294b2..fbee147b0a0 100644
--- a/libs/libbuiltin/compiler-rt/Make.defs
+++ b/libs/libbuiltin/compiler-rt/Make.defs
@@ -108,6 +108,33 @@ ifeq ($(CONFIG_ARCH_X86_64),)
CSRCS := $(filter-out $(x86_80_BIT_SOURCES), $(CSRCS))
endif
+# The Arm builtins ship hand-written VFP assembly whose FPU requirements the
+# wildcard glob above ignores. Upstream compiler-rt selects these files
+# conditionally, so assemble only the ones the configured FPU supports;
+# otherwise single-precision-FPU targets (e.g. Cortex-M33, fpv5-sp-d16) fail
+# with "selected FPU does not support instruction". See apache/nuttx#17386.
+# - chkstk.S / chkstk2.S are Windows/MinGW-only stack probes;
+# - every *vfp.S needs a hardware FPU;
+# - the double-precision *df*vfp.S routines additionally need a
+# double-precision FPU.
+
+ifeq ($(CONFIG_ARCH_ARM),y)
+ COMPILER_RT_ARM_EXCLUDE := chkstk.S chkstk2.S
+ifneq ($(CONFIG_ARCH_FPU),y)
+ COMPILER_RT_ARM_EXCLUDE += $(notdir \
+ $(wildcard compiler-rt/compiler-rt/lib/builtins/arm/*vfp.S))
+else ifneq ($(CONFIG_ARCH_DPFPU),y)
+ COMPILER_RT_ARM_EXCLUDE += adddf3vfp.S divdf3vfp.S eqdf2vfp.S
extendsfdf2vfp.S
+ COMPILER_RT_ARM_EXCLUDE += fixdfsivfp.S fixunsdfsivfp.S floatsidfvfp.S
+ COMPILER_RT_ARM_EXCLUDE += floatunssidfvfp.S gedf2vfp.S gtdf2vfp.S ledf2vfp.S
+ COMPILER_RT_ARM_EXCLUDE += ltdf2vfp.S muldf3vfp.S nedf2vfp.S subdf3vfp.S
+ COMPILER_RT_ARM_EXCLUDE += truncdfsf2vfp.S unorddf2vfp.S
+endif
+ ASRCS := $(filter-out $(addprefix \
+ compiler-rt/compiler-rt/lib/builtins/arm/, $(COMPILER_RT_ARM_EXCLUDE)), \
+ $(ASRCS))
+endif
+
endif
################# Profile Library #################
