[clang] [lld] [llvm] [WIP][IR][Constants] Change the semantic of `ConstantPointerNull` to represent an actual `nullptr` instead of a zero-value pointer (PR #166667)

[Shilei Tian via cfe-commits]

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@@ -182,7 +182,7 @@ define ptr addrspace(3) @addrspacecast_flat_null_to_group() {
 ; CHECK-LABEL: addrspacecast_flat_null_to_group:
 ; CHECK:       ; %bb.0:
 ; CHECK-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; CHECK-NEXT:    v_mov_b32_e32 v0, -1
+; CHECK-NEXT:    v_mov_b32_e32 v0, 0
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shiltian wrote:

This change is wrong. Need to find the right place to do the right value.

https://github.com/llvm/llvm-project/pull/166667