Craig Topper 664663cbbf
[RISCV] Improve 2*XLEN SHL legalization with P extension. (#181056)
For an i64 shift by a constant < 32 on RV32, we can use NSRLI
with 32-ShAmt to calculate the high half of the result.
    
For non-constant shifts, we can use SLX and some bit tricks to
avoid branches. I wanted to use the target independent code from
TargetLowering, but it currently produces worse code.

Assisted-by: claude
2026-02-11 23:32:02 -08:00
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