Using LDC

Generally, LDC should be straightforward to use, like any other compiler. It comes with two different »drivers«, i.e. executables a user invokes to compile D code: ldc2, which offers many customization options, some of which are internal to LLVM, and ldmd2, which tries to accurately replicate the DMD command line interface and can be used as a drop-in replacement for DMD.

Configuration file search path

LDC looks for a file called ldc.conf resp. ldc2.conf in the follow directories in order:

1. current working directory
2. next to binary
3. ~/.ldc
4. user home directory (Windows-only)
5. in an etc directory next to the directory where the binary resides
6. install-prefix (Windows-only)
7. install-prefix/etc
8. install-prefix/etc/ldc
9. /etc
10. /etc/ldc

ldc2 command line options

1. | -mdcompute-targets=<ocl-210,cuda-350>
2. | DCompute targets to generate for:OpenCl (ocl-xy0 for x.y) CUDA (cuda-xy0 for cc x.y)
3. |-

-D	Generate Documentation
-Dd=<docdir>	Write documentation file to <docdir> directory
-Df=<filename>	Write documentation file to <filename>
-H	Generate 'header' file
-Hd=<hdrdir>	Write 'header' file to <hdrdir> directory
-Hf=<filename>	Write 'header' file to <filename>
-Hkeep-all-bodies	Keep all function bodies in .di files
-I=<path>	Where to look for imports
-J=<path>	Where to look for string imports
-L=<linkerflag>	Pass <linkerflag> to the linker
Setting the optimization level:
-O	Equivalent to -O3
-O0	No optimizations (default)
-O1	Simple optimisations
-O2	Good optimisations
-O3	Aggressive optimisations
-O4	Equivalent to -O3
-O5	Equivalent to -O3
-Os	Like -O2 with extra optimizations for size
-Oz	Like -Os but reduces code size further
-X	Generate JSON file
-Xf=<filename>	Write JSON file to <filename>
-aarch64-neon-syntax	Choose style of NEON code to emit from AArch64 backend:
=generic	Emit generic NEON assembly
=apple	Emit Apple-style NEON assembly
-allinst	generate code for all template instantiations
-boundscheck	Enable array bounds check
=off	no array bounds checks
=safeonly	array bounds checks for safe functions only
=on	array bounds checks for all functions
-c	Do not link
-check-printf-calls	Validate printf call format strings against arguments
-code-model	Code model
=default	Target default code model
=small	Small code model
=kernel	Kernel code model
=medium	Medium code model
=large	Large code model
-conf=<filename>	Use configuration file <filename>
-cov	Compile-in code coverage analysis (use -cov=n for n% minimum required coverage)
Allow deprecated code/language features:
-de	Do not allow deprecated features
-d	Silently allow deprecated features
-dw	Warn about the use of deprecated features
-d-debug=<level/idents>	Compile in debug code >= <level> or identified by <idents>.
-d-version=<level/idents>	Compile in version code >= <level> or identified by <idents>
-debuglib=<lib1,lib2,...>	Debug versions of default libraries (overrides previous)
-defaultlib=<lib1,lib2,...>	Default libraries to link with (overrides previous)
-deps=<filename>	Write module dependencies to filename (only imports)
-dip25	implement http://wiki.dlang.org/DIP25 (experimental)
-enable-asserts	(*) Enable assertions
=enable-asserts	(*) Enable assertions
-enable-color	Force colored console output
=enable-color	Force colored console output
-disable-d-passes	Disable all D-specific passes
-disable-fp-elim	Disable frame pointer elimination optimisation
-disable-gc2stack	Disable promotion of GC allocations to stack memory
-enable-inlining	Enable function inlining (default in -O2 and higher)
=enable-inlining	Enable function inlining (default in -O2 and higher)
-enable-invariants	(*) Enable invariants
=enable-invariants	(*) Enable invariants
-disable-linker-strip-dead	Do not try to remove unused symbols during linking
-disable-loop-unrolling	Disable loop unrolling in all relevant passes
-disable-loop-vectorization	Disable the loop vectorization pass
-enable-preconditions	(*) Enable function preconditions
=enable-preconditions	(*) Enable function preconditions
-disable-red-zone	Do not emit code that uses the red zone.
-disable-simplify-drtcalls	Disable simplification of druntime calls
-disable-simplify-libcalls	Disable simplification of well-known C runtime calls
-disable-slp-vectorization	Disable the slp vectorization pass
-enable-contracts	(*) Enable function pre- and post-conditions
=enable-contracts	(*) Enable function pre- and post-conditions
-enable-postconditions	(*) Enable function postconditions
=enable-postconditions	(*) Enable function postconditions
-float-abi	ABI/operations to use for floating-point types:
=default	Target default floating-point ABI
=soft	Software floating-point ABI and operations
=softfp	Soft-float ABI, but hardware floating-point instructions
=hard	Hardware floating-point ABI and instructions
-fthread-model	Thread model
=global-dynamic	Global dynamic TLS model (default)
=local-dynamic	Local dynamic TLS model
=initial-exec	Initial exec TLS model
=local-exec	Local exec TLS model
Generating debug information:
-g	Generate debug information
-gc	Same as -g, but pretend to be C
-hash-threshold=<uint>	hash symbol names longer than this threshold (experimental)
-help	Display available options (-help-hidden for more)
-ignore	Ignore unsupported pragmas
-ir2obj-cache=<cache dir>	Use <cache dir> to cache object files for whole IR modules (experimental)
-ir2obj-cache-prune	Enable cache pruning.
-ir2obj-cache-prune-expiration=<dur>	Sets the pruning expiration time of cache files to <dur> seconds (default: 1 week). Implies -ir2obj-cache-prune.
-ir2obj-cache-prune-interval=<dur>	Sets the cache pruning interval to <dur> seconds (default: 20 min). Set to 0 to force pruning. Implies -ir2obj-cache-prune.
-ir2obj-cache-prune-maxbytes=<size>	Sets the maximum cache size to <size> bytes. Implies -ir2obj-cache-prune.
-ir2obj-cache-prune-maxpercentage=<perc>	Sets the cache size limit to <perc> percent of the available space (default: 75%). Implies -ir2obj-cache-prune.
-lib	Create static library
-link-debuglib	Link with libraries specified in -debuglib, not -defaultlib
-linkonce-templates	Use linkonce_odr linkage for template symbols instead of weak_odr
-m32	32 bit target
-m64	64 bit target
-main	Add empty main() (e.g. for unittesting)
-march=<string>	Architecture to generate code for:
-mattr=<a1,+a2,-a3,...>	Target specific attributes (-mattr=help for details)
-mcpu=<cpu-name>	Target a specific cpu type (-mcpu=help for details)
-mtriple=<string>	Override target triple
-noasm	Disallow use of inline assembler
-nogc	Do not allow code that generates implicit garbage collector calls
-o-	Do not write object file
-od=<objdir>	Write object files to directory <objdir>
-of=<filename>	Use <filename> as output file name
-op	Do not strip paths from source file
-oq	Write object files with fully qualified names
-output-bc	Write LLVM bitcode
-output-ll	Write LLVM IR
-output-o	Write native object
-output-s	Write native assembly
-property	Enforce property syntax
-release	Disables asserts, invariants, contracts and boundscheck
-relocation-model	Relocation model
=default	Target default relocation model
=static	Non-relocatable code
=pic	Fully relocatable, position independent code
=dynamic-no-pic	Relocatable external references, non-relocatable code
-run=<string>	Runs the resulting program, passing the remaining arguments to it
-sanitize	Enable runtime instrumentation for bug detection
=address	memory errors
=memory	memory errors
=thread	race detection
-shared	Create shared library
-singleobj	Create only a single output object file
-static	Create a statically linked binary, including all system dependencies
-template-depth=<uint>	(experimental) set maximum number of nested template instantiations
-transition=<idents>	help with language change identified by <idents>, use ? for list
-unittest	Compile in unit tests
-v	Verbose
-v-cg	Verbose codegen
-vcolumns	print character (column) numbers in diagnostics
-verrors=<uint>	limit the number of error messages (0 means unlimited)
-version
Display the version of this program
-vgc	list all gc allocations including hidden ones
-vv	Print front-end/glue code debug log
Warnings:
-w	Enable warnings
-wi	Enable informational warnings
-x86-asm-syntax	Choose style of code to emit from X86 backend:
=att	Emit AT&T-style assembly
=intel	Emit Intel-style assembly