llvm-project

e588c7fa - [X86] Attempt to fold trunc(srl(load(p),amt) -> load(p+amt/8) (#165266)

[X86] Attempt to fold trunc(srl(load(p),amt) -> load(p+amt/8) (#165266) As reported on #164853 - we only attempt to reduce shifted loads for constant shift amounts, but we could do more with non-constant values if value tracking can confirm basic alignments. This patch determines if a truncated shifted load of scalar integer shifts by a byte aligned amount and replaces the non-constant shift amount with a pointer offset instead. I had hoped to make this a generic DAG fold, but reduceLoadWidth isn't ready to be converted to a KnownBits value tracking mechanism, and other targets don't have complex address math like X86. Fixes #164853