Redundant Copy Elimination was eliminating a MOVi32imm -1 when it
determined that the value of the destination register is already -1.
However, it didn't take into account that the MOVi32imm zeroes the upper
32 bits (which are
FFFFFFFF) and therefore cannot be eliminated.
Reviewed By: paulwalker-arm
Differential Revision: https://reviews.llvm.org/D93100
O.getReg() != CmpReg;
}))
continue;
+
+ // Don't remove a move immediate that implicitly defines the upper
+ // bits as different.
+ if (TRI->isSuperRegister(DefReg, KnownReg.Reg) && KnownReg.Imm < 0)
+ continue;
}
if (IsCopy)
bb.2:
RET_ReallyLR
...
-# Eliminate redundant MOVi32imm -1 in bb.1
+# Don't eliminate redundant MOVi32imm -1 in bb.1: the upper bits are nonzero.
# Note: 64-bit compare/32-bit move imm
# Kill marker should be removed from compare.
# CHECK-LABEL: name: test21
-# CHECK: ADDSXri $x0, 1, 0, implicit-def $nzcv
+# CHECK: ADDSXri killed $x0, 1, 0, implicit-def $nzcv
# CHECK: bb.1:
-# CHECK-NOT: MOVi32imm
+# CHECK: MOVi32imm
name: test21
tracksRegLiveness: true
body: |