Fast Register Allocator does not update liveness. #168201
Description
Repro
$ ./bin/llc -mtriple=riscv64 -O0 -mtriple=riscv64 -mattr=+m -verify-machineinstrs ../llvm/test/CodeGen/RISCV/constpool-known-bits.ll -debug -print-after-all
# *** IR Dump After Verify generated machine code (machineverifier) ***:
# Machine code for function test: NoPHIs, TracksLiveness, TiedOpsRewritten
Constant Pool:
cp#0: -9191740941672628224, align=8
cp#1: -9191740941672640512, align=8
Function Live Ins: $x10 in %0, $x11 in %1
bb.0.entry:
liveins: $x10, $x11
%1:gpr = COPY killed $x11
%0:gpr = COPY killed $x10
%3:gpr = COPY %1:gpr
%2:gpr = COPY %0:gpr
%4:gpr = SLLI %0:gpr, 32
%5:gpr = SRLI killed %4:gpr, 32
%6:gpr = LUI target-flags(riscv-hi) %const.0
%7:gpr = LD killed %6:gpr, target-flags(riscv-lo) %const.0 :: (load (s64) from constant-pool)
%8:gpr = MUL %5:gpr, killed %7:gpr
%9:gpr = ADDI killed %8:gpr, 127
%10:gpr = MUL %5:gpr, killed %9:gpr
%11:gpr = LUI target-flags(riscv-hi) %const.1
%12:gpr = LD killed %11:gpr, target-flags(riscv-lo) %const.1 :: (load (s64) from constant-pool)
%13:gpr = MUL killed %10:gpr, killed %12:gpr
%14:gpr = ADD killed %13:gpr, %5:gpr
%15:gpr = LUI 1015920
%16:gpr = ADDI killed %15:gpr, 1541
%17:gpr = SLLI killed %16:gpr, 16
%18:gpr = ADDI killed %17:gpr, 1027
%19:gpr = SLLI killed %18:gpr, 20
%20:gpr = ADD killed %14:gpr, killed %19:gpr
$x10 = COPY %20:gpr
PseudoRET implicit killed $x10
# End machine code for function test.********** FAST REGISTER ALLOCATION **********
%1:gpr = COPY killed $x11
Regs: X10_H[P] X11_H=%1
In def of %1 use existing assignment to $x11
Freeing $x11: %1
<< renamable $x11 = COPY killed $x11
# *** IR Dump After Fast Register Allocator (regallocfast) ***:
# Machine code for function test: NoPHIs, TracksLiveness, NoVRegs, TiedOpsRewritten
Constant Pool:
cp#0: -9191740941672628224, align=8
cp#1: -9191740941672640512, align=8
Function Live Ins: $x10, $x11
bb.0.entry:
liveins: $x10, $x11
dead renamable $x11 = COPY renamable $x10
renamable $x10 = SLLI killed renamable $x10, 32
renamable $x11 = SRLI killed renamable $x10, 32
renamable $x10 = LUI target-flags(riscv-hi) %const.0
renamable $x10 = LD killed renamable $x10, target-flags(riscv-lo) %const.0 :: (load (s64) from constant-pool)
renamable $x10 = MUL renamable $x11, killed renamable $x10
renamable $x10 = ADDI killed renamable $x10, 127
renamable $x10 = MUL renamable $x11, killed renamable $x10
renamable $x12 = LUI target-flags(riscv-hi) %const.1
renamable $x12 = LD killed renamable $x12, target-flags(riscv-lo) %const.1 :: (load (s64) from constant-pool)
renamable $x10 = MUL killed renamable $x10, killed renamable $x12
renamable $x10 = ADD killed renamable $x10, killed renamable $x11
renamable $x11 = LUI 1015920
renamable $x11 = ADDI killed renamable $x11, 1541
renamable $x11 = SLLI killed renamable $x11, 16
renamable $x11 = ADDI killed renamable $x11, 1027
renamable $x11 = SLLI killed renamable $x11, 20
renamable $x10 = ADD killed renamable $x10, killed renamable $x11
PseudoRET implicit killed $x10
# End machine code for function test.