[GISel] Teach computeKnownBitsImpl to handle COPY instructions that change bit width. (#118924)

The sexti32 ComplexRenderFn on RISCV calls computeNumSignBits which
calls computeKnownBits.

I encountered a case where we looked through a G_PHI and found a COPY
that was created from an already selected G_TRUNC from s64 to s32. s32
and s64 integers on RISC-V end up in the same register class. s32 G_PHI
is legal to allow f32 phis on RV64. The COPY inherited the types from the
original G_TRUNC so the source and destination virtual registers have
different widths.

This patch uses KnownBits::anyextOrTrunc to adjust the width when they
mismatch.

0 files changed, 0 insertions, 0 deletions