reed kotler
2015-Jan-02 22:24 UTC
[LLVMdev] "ran out of registers during register allocation"
I'm getting this error in RegAllocFast.cpp in compiling one source file
in test-suite as the result of a new Mips fast-isel patch
I was testing.
It apparently just generates bad code and continues?
// Nothing we can do. Report an error and keep going with a bad
allocation.
if (MI->isInlineAsm())
MI->emitError("inline assembly requires more registers than
available");
else
MI->emitError("ran out of registers during register
allocation");
How is it possible to run out of registers during register allocation? Lol.
Reed
Philip Reames
2015-Jan-02 22:41 UTC
[LLVMdev] "ran out of registers during register allocation"
On 01/02/2015 02:24 PM, reed kotler wrote:> I'm getting this error in RegAllocFast.cpp in compiling one source > file in test-suite as the result of a new Mips fast-isel patch > I was testing. > > It apparently just generates bad code and continues? > > // Nothing we can do. Report an error and keep going with a bad > allocation. > if (MI->isInlineAsm()) > MI->emitError("inline assembly requires more registers than > available"); > else > MI->emitError("ran out of registers during register allocation"); > > > How is it possible to run out of registers during register allocation? > Lol.This seems to be one of the more common errors when you get a MI instruction definition wrong. In particular, I saw this a lot when experimenting with various lowering strategies for the statepoint work. I'd suggest trying to reduce the example using bugpoint and looking closely at the machine instructions.> > Reed > _______________________________________________ > LLVM Developers mailing list > LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
reed kotler
2015-Jan-02 22:42 UTC
[LLVMdev] "ran out of registers during register allocation"
On 01/02/2015 02:41 PM, Philip Reames wrote:> > On 01/02/2015 02:24 PM, reed kotler wrote: >> I'm getting this error in RegAllocFast.cpp in compiling one source >> file in test-suite as the result of a new Mips fast-isel patch >> I was testing. >> >> It apparently just generates bad code and continues? >> >> // Nothing we can do. Report an error and keep going with a bad >> allocation. >> if (MI->isInlineAsm()) >> MI->emitError("inline assembly requires more registers than >> available"); >> else >> MI->emitError("ran out of registers during register allocation"); >> >> >> How is it possible to run out of registers during register >> allocation? Lol. > This seems to be one of the more common errors when you get a MI > instruction definition wrong. In particular, I saw this a lot when > experimenting with various lowering strategies for the statepoint > work. I'd suggest trying to reduce the example using bugpoint and > looking closely at the machine instructions. >>Okay. THanks. I'll take a look.>> Reed >> _______________________________________________ >> LLVM Developers mailing list >> LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu >> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev >
reed kotler
2015-Jan-03 03:32 UTC
[LLVMdev] "ran out of registers during register allocation"
It seems like it might be a legitimate complaint from the register allocator. It's trying to get an accumulator (not a general purpose register) and the accumulator is 64 bit. It's using a part of the Mips backend that I have not worked in so I have to research this a bit. The multiply instruction is a pseudo multiply in the mips backend and it needs the accumulator which a special register and there is only one and it has special properties. This may normally be getting sorted out by some code which is not present during fast-isel. On 01/02/2015 02:41 PM, Philip Reames wrote:> > On 01/02/2015 02:24 PM, reed kotler wrote: >> I'm getting this error in RegAllocFast.cpp in compiling one source >> file in test-suite as the result of a new Mips fast-isel patch >> I was testing. >> >> It apparently just generates bad code and continues? >> >> // Nothing we can do. Report an error and keep going with a bad >> allocation. >> if (MI->isInlineAsm()) >> MI->emitError("inline assembly requires more registers than >> available"); >> else >> MI->emitError("ran out of registers during register allocation"); >> >> >> How is it possible to run out of registers during register >> allocation? Lol. > This seems to be one of the more common errors when you get a MI > instruction definition wrong. In particular, I saw this a lot when > experimenting with various lowering strategies for the statepoint > work. I'd suggest trying to reduce the example using bugpoint and > looking closely at the machine instructions. >> >> Reed >> _______________________________________________ >> LLVM Developers mailing list >> LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu >> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev >