Jeremy Morse 7a8e30eba0 [DebugInfo][InstrRef][1/4] Support transformations that widen values ... Very late in compilation, backends like X86 will perform optimisations like this: $cx = MOV16rm $rax, ... -> $rcx = MOV64rm $rax, ... Widening the load from 16 bits to 64 bits. SEeing how the lower 16 bits remain the same, this doesn't affect execution. However, any debug instruction reference to the defined operand now refers to a 64 bit value, nto a 16 bit one, which might be unexpected. Elsewhere in codegen, there's often this pattern: CALL64pcrel32 @foo, implicit-def $rax %0:gr64 = COPY $rax %1:gr32 = COPY %0.sub_32bit Where we want to refer to the definition of $eax by the call, but don't want to refer the copies (they don't define values in the way LiveDebugValues sees it). To solve this, add a subregister field to the existing "substitutions" facility, so that we can describe a field within a larger value definition. I would imagine that this would be used most often when a value is widened, and we need to refer to the original, narrower definition. Differential Revision: https://reviews.llvm.org/D88891		2021-07-01 11:19:27 +01:00
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llvm	[DebugInfo][InstrRef][1/4] Support transformations that widen values	2021-07-01 11:19:27 +01:00
llvm-c	[ORC] Rename TargetProcessControl to ExecutorProcessControl. NFC.	2021-07-01 13:31:12 +10:00