[llvm] [MCP] Skip invalidating constant regs during forward propagation (PR #111129)

[Matt Arsenault via llvm-commits]

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@@ -885,6 +885,10 @@ void MachineCopyPropagation::ForwardCopyPropagateBlock(MachineBasicBlock &MBB) {
       assert(!Reg.isVirtual() &&
              "MachineCopyPropagation should be run after register allocation!");
 
+      // Skip invalidating constant registers.
+      if (MRI->isReserved(Reg) && MRI->isConstantPhysReg(Reg))
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arsenm wrote:

Don't need the reserved check? 

https://github.com/llvm/llvm-project/pull/111129