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+This is a basic compiler driver for the PIC16 toolchain that shows how to create
+your own llvmc-based drivers. It is based on the examples/Skeleton template.
+
+The PIC16 toolchain looks like this:
+
+clang-cc (FE) -> llvm-ld (optimizer) -> llc (codegen) -> native-as -> native-ld
+
+Following features were requested by Sanjiv:
+
+From: Sanjiv Gupta <sanjiv.gupta <at> microchip.com>
+Subject: Re: llvmc for PIC16
+Newsgroups: gmane.comp.compilers.llvm.devel
+Date: 2009-06-05 06:51:14 GMT
+
+The salient features that we want to have in the driver are:
+1. llvm-ld will be used as "The Optimizer".
+2. If the user has specified to generate the final executable, then
+llvm-ld should run on all the .bc files generated by clang and create a
+single optimized .bc file for further tools.
+3. -Wo <options> - pass optimizations to the llvm-ld
+4. mcc16 -Wl <options> - pass options to native linker.
+5. mcc16 -Wa <options> - pass options to native assembler.
+
+Here are some example command lines and sample command invocations as to
+what should be done.
+
+$ mcc16 -S foo.c
+// [clang-cc foo.c] -> foo.bc
+// [llvm-ld foo.bc] -> foo.opt.bc
+// [llc foo.opt.bc] -> foo.s
+
+$ mcc16 -S foo.c bar.c
+// [clang-cc foo.c] -> foo.bc
+// [llvm-ld foo.bc] -> foo.opt.bc
+// [llc foo.opt.bc] -> foo.s
+// [clang-cc bar.c] -> bar.bc
+// [llvm-ld bar.bc] -> bar.opt.bc
+// [llc bar.opt.bc] -> bar.s
+
+** Use of -g causes llvm-ld to run with -disable-opt
+$ mcc16 -S -g foo.c
+// [clang-cc foo.c] -> foo.bc
+// [llvm-ld -disable-opt foo.bc] -> foo.opt.bc
+// [llc foo.opt.bc] -> foo.s
+
+** -I is passed to clang-cc, -pre-RA-sched=list-burr to llc.
+$ mcc16 -S -g -I ../include -pre-RA-sched=list-burr foo.c
+// [clang-cc -I ../include foo.c] -> foo.bc
+// [llvm-ld -disable-opt foo.bc] -> foo.opt.bc
+// [llc -pre-RA-sched=list-burr foo.opt.bc] -> foo.s
+
+** -Wo passes options to llvm-ld
+$ mcc16 -Wo=opt1,opt2 -S -I ../include -pre-RA-sched=list-burr foo.c
+// [clang-cc -I ../include foo.c] -> foo.bc
+// [llvm-ld -opt1 -opt2 foo.bc] -> foo.opt.bc
+// [llc -pre-RA-sched=list-burr foo.opt.bc] -> foo.s
+
+** -Wa passes options to native as.
+$ mcc16 -c foo.c -Wa=opt1
+// [clang-cc foo.c] -> foo.bc
+// [llvm-ld foo.bc] -> foo.opt.bc
+// [llc foo.opt.bc] -> foo.s
+// [native-as -opt1 foo.s] -> foo.o
+
+$ mcc16 -Wo=opt1 -Wl=opt2 -Wa=opt3 foo.c bar.c
+// [clang-cc foo.c] -> foo.bc
+// [clang-cc bar.c] -> bar.bc
+// [llvm-ld -opt1 foo.bc bar.bc] -> a.out.bc
+// [llc a.out.bc] -> a.out.s
+// [native-as -opt3 a.out.s] -> a.out.o
+// [native-ld -opt2 a.out.o] -> a.out
+
+Is this achievable by a tablegen based driver ?
+
+- Sanjiv