Update makefiles for clang 14 or newer #6
Description
I'm trying these examples on clang v14 and v15 (on an Ubuntu box) and they fail with some variant of ld.lld: error: undefined symbol: __enzyme_autodiff or square.c:(.text+0x3a): undefined reference to '__enzyme_autodiff' depending on what linker I use.
For example, using regular gnu ld and making the following changes to the Makefile
$ git diff --word-diff Makefile
diff --git a/1_square/Makefile b/1_square/Makefile
index c223268..b4f278a 100644
--- a/1_square/Makefile
+++ b/1_square/Makefile
@@ -4,7 +4,8 @@ clean:
rm -f *.o *.ll
%.o: %.c
[-../dockerscript.sh clang-12 /host/$^-]{+clang $^+} -O3 -Xclang -load -Xclang [-/Enzyme/enzyme/build/Enzyme/ClangEnzyme-12.so-]{+../../Enzyme/enzyme/build/Enzyme/LLVMEnzyme-14.so+} -ffast-math -o [-/host/$@-]{+$@+}
I obtain:
clang square.c -O3 -Xclang -load -Xclang ../../Enzyme/enzyme/build/Enzyme/LLVMEnzyme-14.so -ffast-math -o square.o
/usr/bin/ld: /tmp/square-977b64.o: in function `main':
square.c:(.text+0x3a): undefined reference to `__enzyme_autodiff'
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [Makefile:7: square.o] Error 1
Adding -fpass-plugin=../../Enzyme/enzyme/build/Enzyme/LLVMEnzyme-14.so for the new pass-manager does not change anything.
The possibly most consequential change to the Makefile is probably the switch from ClangEnzyme-version.so to LLVMEnzyme-version.so. Is that the root cause to this problem? If so, how does one build the former? There is no mention of ClangEnzyme in the cmake_install.cmake of Enzyme version da97fda9aeef27e827a8803f31c40d1b90d0f4a0 (origin/jmp/dataflow-activity-analysis).
As a workaround, I can manually run each step as described at https://enzyme.mit.edu/getting_started/UsingEnzyme/ and that works:
$ clang square.c -S -emit-llvm -o input.ll -O2 -fno-vectorize -fno-slp-vectorize -fno-unroll-loops
$ opt -enable-new-pm=0 input.ll -load=../../Enzyme/enzyme/build/Enzyme/LLVMEnzyme-14.so -enzyme -o output.ll -S
$ opt output.ll -O2 -o output_opt.ll -S
$ clang output_opt.ll -o a.exe
$ ./a.exe 3.14
Gradient square(3.140000) = 6.280000
However that is good only for single-file examples. The optcommand can't be made to work for multisource, as far as I understand it, since both opt and clang -S can only deal with one source file at the time and one would need two for this purpose:
$ clang multisource.c -S -emit-llvm -o multisource.ll -fno-vectorize -fno-slp-vectorize -fno-unroll-loops
$ clang myblas.c -S -emit-llvm -o myblas.ll -fno-vectorize -fno-slp-vectorize -fno-unroll-loops
$ opt -enable-new-pm=0 myblas.ll -load=../../Enzyme/enzyme/build/Enzyme/LLVMEnzyme-14.so -enzyme -o myblas_out.ll -S
$ opt -enable-new-pm=0 multisource.ll -load=../../Enzyme/enzyme/build/Enzyme/LLVMEnzyme-14.so -enzyme -o multisource_out.ll -S
error: <unknown>:0:0: in function preprocess_dotabs double (%struct.complex*, %struct.complex*, i32): Enzyme: No reverse pass found for myblas_cabs
at context: %7 = call double @myblas_cabs(double %5, double %6) #7
$ opt -enable-new-pm=0 myblas.ll multisource.ll -load=../../Enzyme/enzyme/build/Enzyme/LLVMEnzyme-14.so -enzyme -o multisource+myblas_out.ll -S
opt: Too many positional arguments specified!
Can specify at most 1 positional arguments: See: opt --help
$ clang multisource.c myblas.c -S -emit-llvm -o multisource+myblas.ll -fno-vectorize -fno-slp-vectorize -fno-unroll-loops
clang: error: cannot specify -o when generating multiple output files
so how can one fix that case?
@wsmoses sorry if the question is very trivial, but I've been unable to find guidance in the existing examples and documentation, either here or on https://github.com/EnzymeAD/Enzyme