[MachineVerifier] Handle the PHI node for verifyLiveVariables()

Summary:
When doing MachineVerifier for LiveVariables, the MachineVerifier pass
will calculate the LiveVariables, and compares the result with the
result livevars pass gave. If they are different, verifyLiveVariables()
will give error.

But when we calculate the LiveVariables in MachineVerifier, we don't
consider the PHI node, while livevars considers.

This patch is to fix above bug.

Reviewed By: bjope

Differential Revision: https://reviews.llvm.org/D80274

Author: zhangkangcool

llvm/lib/CodeGen/MachineVerifier.cpp

@@ -132,7 +132,8 @@ namespace {
       bool reachable = false;
 
       // Vregs that must be live in because they are used without being
-      // defined. Map value is the user.
+      // defined. Map value is the user. vregsLiveIn doesn't include regs
+      // that only are used by PHI nodes.
       RegMap vregsLiveIn;
 
       // Regs killed in MBB. They may be defined again, and will then be in both
@@ -2302,6 +2303,23 @@ void MachineVerifier::calcRegsRequired() {
       if (PInfo.addRequired(MInfo.vregsLiveIn))
         todo.insert(Pred);
     }
+
+    // Handle the PHI node.
+    for (const MachineInstr &MI : MBB.phis()) {
+      for (unsigned i = 1, e = MI.getNumOperands(); i != e; i += 2) {
+        // Skip those Operands which are undef regs or not regs.
+        if (!MI.getOperand(i).isReg() || !MI.getOperand(i).readsReg())
+          continue;
+
+        // Get register and predecessor for one PHI edge.
+        Register Reg = MI.getOperand(i).getReg();
+        const MachineBasicBlock *Pred = MI.getOperand(i + 1).getMBB();
+
+        BBInfo &PInfo = MBBInfoMap[Pred];
+        if (PInfo.addRequired(Reg))
+          todo.insert(Pred);
+      }
+    }
   }
 
   // Iteratively push vregsRequired to predecessors. This will converge to the

llvm/test/CodeGen/PowerPC/livevars-crash1.mir

@@ -1,6 +1,6 @@
-# RUN: not --crash llc -mtriple powerpc64le-unknown-linux-gnu %s -o - 2>&1 \
-# RUN:   -run-pass=livevars,phi-node-elimination -verify-machineinstrs \
-# RUN:   | FileCheck %s
+# RUN: llc -mtriple powerpc64le-unknown-linux-gnu %s -o - 2>&1 \
+# RUN:   -run-pass=livevars,phi-node-elimination -verify-machineinstrs | \
+# RUN:  FileCheck %s
 
 --- |
   ; Function Attrs: noreturn nounwind
@@ -82,9 +82,46 @@ body:             |
     STD %3, 0, %4 :: (store 8 into %ir.p)
     B %bb.1
 
+  ; CHECK-LABEL: name: zext_free
+  ; CHECK: bb.0.entry:
+  ; CHECK:   successors: %bb.1(0x80000000)
+  ; CHECK:   liveins: $x3
+
+  ; CHECK:   %4:g8rc_and_g8rc_nox0 = COPY killed $x3
+  ; CHECK:   %0:g8rc = LD 0, %4 :: (dereferenceable load 8 from %ir.p)
+  ; CHECK:    %12:g8rc_and_g8rc_nox0 = COPY killed %0
+
+  ; CHECK: bb.1.loop:
+  ; CHECK:   successors: %bb.1(0x20000000), %bb.2(0x60000000)
+
+  ; CHECK:   %1:g8rc_and_g8rc_nox0 = COPY killed %12
+  ; CHECK:   %5:gprc = LBZ 0, %1 :: (load 1 from %ir.0)
+  ; CHECK:   %6:crrc = CMPWI killed %5, 0
+  ; CHEXK:   %7:crbitrc = COPY killed %6.sub_eq
+  ; CHECK:   %2:g8rc = nuw ADDI8 %1, 1
+  ; CHECK:   STD %2, 0, %4 :: (store 8 into %ir.p)
+  ; CHECK:   %8:gprc = LBZ 1, %1 :: (load 1 from %ir.incdec.ptr)
+  ; CHECK:   %12:g8rc_and_g8rc_nox0 = COPY %2
+  ; CHECK:   BCn killed %7, %bb.1
+  ; CHECK:   B %bb.2
+
+  ; CHECK: bb.2.loop:
+  ; CHECK:   successors: %bb.3(0x55555555), %bb.1(0x2aaaaaab)
+
+  ; CHECK:   %9:crrc = CMPWI killed %8, 0
+  ; CHECK:   %10:crbitrc = COPY killed %9.sub_eq
+  ; CHECK:   %12:g8rc_and_g8rc_nox0 = COPY killed %2
+  ; CHECK:   BC killed %10, %bb.1
+  ; CHECK:   B %bb.3
+
+  ; CHECK: bb.3.if.then3:
+  ; CHECK:   successors: %bb.1(0x80000000)
+
+  ; CHECK:   %3:g8rc = nuw ADDI8 killed %1, 2
+  ; CHECK:   STD %3, 0, %4 :: (store 8 into %ir.p)
+  ; CHECK:   %12:g8rc_and_g8rc_nox0 = COPY killed %3
+  ; CHECK:   B %bb.1
+
+
 ...
-# CHECK-LABEL: Bad machine code: LiveVariables: Block should not be in AliveBlocks
-# CHECK-NEXT:  - function:    zext_free
-# CHECK-NEXT:  - basic block: %bb.2 loop
-# CHECK-NEXT:  Virtual register %2 is not needed live through the block.
-# CHECK-NEXT:  LLVM ERROR: Found 1 machine code errors.
+

llvm/test/CodeGen/PowerPC/livevars-crash2.mir

@@ -1,6 +1,6 @@
-# RUN: not --crash llc -mtriple powerpc64le-unknown-linux-gnu %s -o - 2>&1 \
-# RUN:   -run-pass=livevars,phi-node-elimination -verify-machineinstrs \
-# RUN:   | FileCheck %s
+# RUN: llc -mtriple powerpc64le-unknown-linux-gnu %s -o - 2>&1 \
+# RUN:   -run-pass=livevars,phi-node-elimination -verify-machineinstrs | \
+# RUN:   FileCheck %s
 
 --- |
   define float @testfloatslt(float %c1, float %c2, float %c3, float %c4, float %a1, float %a2) {
@@ -176,20 +176,44 @@ body:             |
     STD %3, 0, %4 :: (store 8 into %ir.p)
     B %bb.1
 
-...
+  ; CHECK-LABEL: name: testfloatslt
+  ; CHECK: bb.0.entry:
+  ; CHECK:   successors: %bb.1(0x80000000)
+  ; CHECK:   liveins: $x3
+
+  ; CHECK:   %4:g8rc_and_g8rc_nox0 = COPY killed $x3
+  ; CHECK:   %0:g8rc = LD 0, %4 :: (dereferenceable load 8 from %ir.p)
+  ; CHECK:   %12:g8rc_and_g8rc_nox0 = COPY killed %0
+
+  ; CHECK: bb.1.loop:
+  ; CHECK:   successors: %bb.1(0x20000000), %bb.2(0x60000000)
+
+  ; CHECK:   %1:g8rc_and_g8rc_nox0 = COPY killed %12
+  ; CHECK:   %5:gprc = LBZ 0, %1 :: (load 1 from %ir.0)
+  ; CHECK:   %6:crrc = CMPWI killed %5, 0
+  ; CEHCK:   %7:crbitrc = COPY killed %6.sub_eq
+  ; CHECK:   %2:g8rc = nuw ADDI8 %1, 1
+  ; CHECK:   STD %2, 0, %4 :: (store 8 into %ir.p)
+  ; CHECK:   %8:gprc = LBZ 1, %1 :: (load 1 from %ir.incdec.ptr)
+  ; CHECK:   %12:g8rc_and_g8rc_nox0 = COPY %2
+  ; CHECK:   BCn killed %7, %bb.1
+  ; CHECK:   B %bb.2
 
-# CHECK-LABEL: Bad machine code: LiveVariables: Block should not be in AliveBlocks
-# CHECK-NEXT:  - function:    testfloatslt
-# CHECK-NEXT:  - basic block: %bb.1 entry
-# CHECK-NEXT:  Virtual register %4 is not needed live through the block.
+  ; CHECK: bb.2.loop:
+  ; CHECK:   successors: %bb.3(0x55555555), %bb.1(0x2aaaaaab)
 
-# CHECK-LABEL: Bad machine code: LiveVariables: Block should not be in AliveBlocks
-# CHECK-NEXT:  - function:    testfloatslt
-# CHECK-NEXT:  - basic block: %bb.1 entry
-# CHECK-NEXT:  Virtual register %5 is not needed live through the block.
+  ; CHECK:   %9:crrc = CMPWI killed %8, 0
+  ; CHECK:   %10:crbitrc = COPY killed %9.sub_eq
+  ; CHECK:   %12:g8rc_and_g8rc_nox0 = COPY killed %2
+  ; CHECK:   BC killed %10, %bb.1
+  ; CHECK:   B %bb.3
 
-# CHECK-LABEL: Bad machine code: LiveVariables: Block should not be in AliveBlocks
-# CHECK-NEXT:  - function:    testfloatslt
-# CHECK-NEXT:  - basic block: %bb.2 entry
-# CHECK-NEXT:  Virtual register %5 is not needed live through the block.
-# CHECK-NEXT:  LLVM ERROR: Found 3 machine code errors.
+  ; CHECK: bb.3.if.then3:
+  ; CHECK:   successors: %bb.1(0x80000000)
+
+  ; CHECK:   %3:g8rc = nuw ADDI8 killed %1, 2
+  ; CHECK:   STD %3, 0, %4 :: (store 8 into %ir.p)
+  ; CHECK:   %12:g8rc_and_g8rc_nox0 = COPY killed %3
+  ; CHECK:   B %bb.1
+
+...