[CGP] Fix the crash for combining address mode when having cyclic dependency

In the combination of addressing modes, when replacing the matched phi nodes,
sometimes the phi node to be replaced has been modified. For example,
there’s matcher set [A, B] and [C, A], which will have cyclic dependency:
A is replaced by B and C will be replaced by A. Because we tried to match new phi node
to another new phi node, we should ignore new phi nodes when mapping new phi node to old one.

Reviewed By: skatkov

Differential Revision: https://reviews.llvm.org/D108635

Author: wweiandrew

llvm/lib/CodeGen/CodeGenPrepare.cpp

@@ -3718,7 +3718,8 @@ class AddressingModeCombiner {
       // Traverse all Phis until we found equivalent or fail to do that.
       bool IsMatched = false;
       for (auto &P : PHI->getParent()->phis()) {
-        if (&P == PHI)
+        // Skip new Phi nodes.
+        if (PhiNodesToMatch.count(&P))
           continue;
         if ((IsMatched = MatchPhiNode(PHI, &P, Matched, PhiNodesToMatch)))
           break;

llvm/test/Transforms/CodeGenPrepare/AArch64/combine-address-mode.ll

@@ -0,0 +1,78 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -codegenprepare -mtriple=aarch64-none-linux-gnu < %s | FileCheck %s
+
+@_MergedGlobals = external dso_local global <{ i32, i32 }>, align 4
+
+define dso_local i32 @f(i1 %a, i8 %b) local_unnamed_addr {
+; CHECK-LABEL: @f(
+; CHECK-NEXT:    br label [[TMP6:%.*]]
+; CHECK:       1:
+; CHECK-NEXT:    br i1 [[A:%.*]], label [[TMP2:%.*]], label [[TMP6]]
+; CHECK:       2:
+; CHECK-NEXT:    [[TMP3:%.*]] = phi i32* [ getelementptr inbounds (<{ i32, i32 }>, <{ i32, i32 }>* @_MergedGlobals, i32 0, i32 1), [[TMP1:%.*]] ], [ [[TMP16:%.*]], [[TMP14:%.*]] ]
+; CHECK-NEXT:    [[TMP4:%.*]] = phi i32* [ getelementptr inbounds (<{ i32, i32 }>, <{ i32, i32 }>* @_MergedGlobals, i32 0, i32 1), [[TMP1]] ], [ [[TMP15:%.*]], [[TMP14]] ]
+; CHECK-NEXT:    ret i32 0
+; CHECK:       5:
+; CHECK-NEXT:    br label [[TMP6]]
+; CHECK:       6:
+; CHECK-NEXT:    [[TMP7:%.*]] = phi i32* [ getelementptr inbounds (<{ i32, i32 }>, <{ i32, i32 }>* @_MergedGlobals, i32 0, i32 0), [[TMP0:%.*]] ], [ [[TMP3]], [[TMP5:%.*]] ], [ getelementptr inbounds (<{ i32, i32 }>, <{ i32, i32 }>* @_MergedGlobals, i32 0, i32 1), [[TMP1]] ]
+; CHECK-NEXT:    [[TMP8:%.*]] = phi i32* [ getelementptr inbounds (<{ i32, i32 }>, <{ i32, i32 }>* @_MergedGlobals, i32 0, i32 0), [[TMP0]] ], [ [[TMP4]], [[TMP5]] ], [ getelementptr inbounds (<{ i32, i32 }>, <{ i32, i32 }>* @_MergedGlobals, i32 0, i32 1), [[TMP1]] ]
+; CHECK-NEXT:    br label [[TMP9:%.*]]
+; CHECK:       9:
+; CHECK-NEXT:    [[TMP10:%.*]] = phi i32* [ [[TMP16]], [[TMP14]] ], [ [[TMP7]], [[TMP6]] ]
+; CHECK-NEXT:    [[TMP11:%.*]] = phi i32* [ [[TMP16]], [[TMP14]] ], [ [[TMP8]], [[TMP6]] ]
+; CHECK-NEXT:    [[TMP12:%.*]] = phi i32* [ [[TMP15]], [[TMP14]] ], [ [[TMP8]], [[TMP6]] ]
+; CHECK-NEXT:    br i1 [[A]], label [[TMP14]], label [[TMP13:%.*]]
+; CHECK:       13:
+; CHECK-NEXT:    store i32 5, i32* [[TMP11]], align 4
+; CHECK-NEXT:    br label [[TMP14]]
+; CHECK:       14:
+; CHECK-NEXT:    [[TMP15]] = phi i32* [ [[TMP12]], [[TMP13]] ], [ [[TMP10]], [[TMP9]] ]
+; CHECK-NEXT:    [[TMP16]] = phi i32* [ [[TMP11]], [[TMP13]] ], [ [[TMP10]], [[TMP9]] ]
+; CHECK-NEXT:    br i1 [[A]], label [[TMP2]], label [[TMP9]]
+;
+  br label %11
+
+1:                                                ; No predecessors!
+  br i1 %a, label %2, label %10
+
+2:                                                ; preds = %22, %1
+  %3 = phi i32* [ getelementptr inbounds (<{ i32, i32 }>, <{ i32, i32 }>* @_MergedGlobals, i32 0, i32 1), %1 ], [ %21, %22 ]
+  %4 = phi i32* [ getelementptr inbounds (<{ i32, i32 }>, <{ i32, i32 }>* @_MergedGlobals, i32 0, i32 1), %1 ], [ %20, %22 ]
+  ret i32 0
+
+5:                                                ; No predecessors!
+  %6 = icmp ugt i8 %b, 50
+  br label %7
+
+7:                                                ; preds = %10, %5
+  %8 = phi i32* [ %3, %5 ], [ getelementptr inbounds (<{ i32, i32 }>, <{ i32, i32 }>* @_MergedGlobals, i32 0, i32 1), %10 ]
+  %9 = phi i32* [ %4, %5 ], [ getelementptr inbounds (<{ i32, i32 }>, <{ i32, i32 }>* @_MergedGlobals, i32 0, i32 1), %10 ]
+  br label %11
+
+10:                                               ; preds = %1
+  br label %7
+
+11:                                               ; preds = %7, %0
+  %12 = phi i32* [ getelementptr inbounds (<{ i32, i32 }>, <{ i32, i32 }>* @_MergedGlobals, i32 0, i32 0), %0 ], [ %8, %7 ]
+  %13 = phi i32* [ getelementptr inbounds (<{ i32, i32 }>, <{ i32, i32 }>* @_MergedGlobals, i32 0, i32 0), %0 ], [ %9, %7 ]
+  br label %14
+
+14:                                               ; preds = %19, %11
+  %15 = phi i32* [ %21, %19 ], [ %12, %11 ]
+  %16 = phi i32* [ %21, %19 ], [ %13, %11 ]
+  %17 = phi i32* [ %20, %19 ], [ %13, %11 ]
+  br i1 %a, label %19, label %18
+
+18:                                               ; preds = %14
+  store i32 5, i32* %16, align 4
+  br label %19
+
+19:                                               ; preds = %18, %14
+  %20 = phi i32* [ %17, %18 ], [ %15, %14 ]
+  %21 = phi i32* [ %16, %18 ], [ %15, %14 ]
+  br i1 %a, label %22, label %14
+
+22:                                               ; preds = %19
+  br label %2
+}