From 46f23e13d06267911d25afe4d00444d9a3f58d2f Mon Sep 17 00:00:00 2001
From: Krishnam Tibrewala <krishnam.tibrewala@amd.com>
Date: Wed, 11 Sep 2024 17:56:35 -0700
Subject: [PATCH] [AIEX] Fix AIEEliminateDuplicatePHI pass

---
 .../Target/AIE/AIEEliminateDuplicatePHI.cpp   | 12 ++---
 .../GlobalISel/eliminate-duplicate-phi.mir    | 50 +++++++++++++++++++
 2 files changed, 53 insertions(+), 9 deletions(-)

diff --git a/llvm/lib/Target/AIE/AIEEliminateDuplicatePHI.cpp b/llvm/lib/Target/AIE/AIEEliminateDuplicatePHI.cpp
index a3ab92e3b674..dfab33dda816 100644
--- a/llvm/lib/Target/AIE/AIEEliminateDuplicatePHI.cpp
+++ b/llvm/lib/Target/AIE/AIEEliminateDuplicatePHI.cpp
@@ -120,18 +120,12 @@ class AIEEliminateDuplicatePHI : public MachineFunctionPass {
   bool processMBB(MachineBasicBlock &MBB, MachineRegisterInfo &MRI,
                   MachineIRBuilder &MIB, GISelObserverWrapper &Observer) {
     bool Changed = false;
-    auto LastPHI = MBB.getFirstNonPHI();
+    auto FirstNonPHI = MBB.getFirstNonPHI();
     for (auto &MI : make_early_inc_range(MBB.phis())) {
       if (!isPointerTypePHI(MRI, MI))
         continue;
-
-      // Ensure that next MI is valid
-      auto NextMI = std::next(MachineBasicBlock::instr_iterator(MI));
-      if (NextMI == MBB.instr_end() || NextMI == LastPHI)
-        break;
-
-      for (auto &PHI : make_early_inc_range(make_range(
-               NextMI, MachineBasicBlock::instr_iterator(*LastPHI)))) {
+      for (auto &PHI : make_early_inc_range(
+               make_range(++MachineBasicBlock::iterator(MI), FirstNonPHI))) {
         if (!isPointerTypePHI(MRI, PHI))
           continue;
         if (MI.isIdenticalTo(PHI, MachineInstr::IgnoreDefs)) {
diff --git a/llvm/test/CodeGen/AIE/GlobalISel/eliminate-duplicate-phi.mir b/llvm/test/CodeGen/AIE/GlobalISel/eliminate-duplicate-phi.mir
index 9ef024ecf54f..af134afddec3 100644
--- a/llvm/test/CodeGen/AIE/GlobalISel/eliminate-duplicate-phi.mir
+++ b/llvm/test/CodeGen/AIE/GlobalISel/eliminate-duplicate-phi.mir
@@ -232,3 +232,53 @@ body:             |
     %5:_(p0) = G_PTR_ADD %3:_, %4:_(s20)
     G_BR %bb.4
 ...
+
+---
+name:            test_two_PHI_nobranch
+legalized:       false
+tracksRegLiveness: true
+body:             |
+  ; CHECK-LABEL: name: test_two_PHI_nobranch
+  ; CHECK: bb.0:
+  ; CHECK-NEXT:   successors: %bb.1(0x40000000), %bb.2(0x40000000)
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 0
+  ; CHECK-NEXT:   [[C1:%[0-9]+]]:_(p0) = G_CONSTANT i20 1
+  ; CHECK-NEXT:   [[C2:%[0-9]+]]:_(p0) = G_CONSTANT i20 2
+  ; CHECK-NEXT:   G_BRCOND [[C]](s32), %bb.1
+  ; CHECK-NEXT:   G_BR %bb.2
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.1:
+  ; CHECK-NEXT:   successors: %bb.3(0x80000000)
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   G_BR %bb.3
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.2:
+  ; CHECK-NEXT:   successors: %bb.3(0x80000000)
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   G_BR %bb.3
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.3:
+  ; CHECK-NEXT:   successors: %bb.4(0x80000000)
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   [[PHI:%[0-9]+]]:_(p0) = G_PHI [[C1]](p0), %bb.1, [[C2]](p0), %bb.2
+  ; CHECK-NEXT:   [[PHI1:%[0-9]+]]:_(p0) = G_PHI [[C1]](p0), %bb.1, [[C2]](p0), %bb.2
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.4:
+  ; CHECK-NEXT:   [[COPY:%[0-9]+]]:_(p0) = COPY [[PHI]](p0)
+  bb.0:
+    %1:_(s32) = G_CONSTANT i32 0
+    %2:_(p0) = G_CONSTANT i20 1
+    %3:_(p0) = G_CONSTANT i20 2
+    G_BRCOND %1:_(s32), %bb.1
+    G_BR %bb.2
+  bb.1:
+    G_BR %bb.3
+  bb.2:
+    G_BR %bb.3
+  bb.3:
+    %4:_(p0) = G_PHI %2:_(p0), %bb.1, %3:_(p0), %bb.2
+    %5:_(p0) = G_PHI %2:_(p0), %bb.1, %3:_(p0), %bb.2
+  bb.4:
+    %6:_(p0) = COPY %5:_(p0)
+...