[MachineVerifier] Add TiedOpsRewritten flag to fix verify two-address error

Summary:
Currently, MachineVerifier will attempt to verify that tied operands
satisfy register constraints as soon as the function is no longer in
SSA form. However, PHIElimination will take the function out of SSA
form while TwoAddressInstructionPass will actually rewrite tied operands
to match the constraints. PHIElimination runs first in the pipeline.
Therefore, whenever the MachineVerifier is run after PHIElimination,
it will encounter verification errors on any tied operands.

This patch adds a function property called TiedOpsRewritten that will be
set by TwoAddressInstructionPass and will control when the verifier checks
tied operands.

Reviewed By: nemanjai

Differential Revision: https://reviews.llvm.org/D80538

1 files changed, 10 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/MachineVerifier.cpp b/llvm/lib/CodeGen/MachineVerifier.cpp
index d0568b3..df23ccf 100644
--- a/llvm/lib/CodeGen/MachineVerifier.cpp
+++ b/llvm/lib/CodeGen/MachineVerifier.cpp
@@ -1633,10 +1633,17 @@ MachineVerifier::visitMachineOperand(const MachineOperand *MO, unsigned MONum) {
       }
     }
 
-    // Verify two-address constraints after leaving SSA form.
+    // Verify two-address constraints after the twoaddressinstruction pass.
+    // Both twoaddressinstruction pass and phi-node-elimination pass call
+    // MRI->leaveSSA() to set MF as NoSSA, we should do the verification after
+    // twoaddressinstruction pass not after phi-node-elimination pass. So we
+    // shouldn't use the NoSSA as the condition, we should based on
+    // TiedOpsRewritten property to verify two-address constraints, this
+    // property will be set in twoaddressinstruction pass.
     unsigned DefIdx;
-    if (!MRI->isSSA() && MO->isUse() &&
-        MI->isRegTiedToDefOperand(MONum, &DefIdx) &&
+    if (MF->getProperties().hasProperty(
+            MachineFunctionProperties::Property::TiedOpsRewritten) &&
+        MO->isUse() && MI->isRegTiedToDefOperand(MONum, &DefIdx) &&
         Reg != MI->getOperand(DefIdx).getReg())
       report("Two-address instruction operands must be identical", MO, MONum);