[CGP] Fix the remove of matched phis in complex addressing mode

When we replace the Phi we created with matched ones it is possible that
there are two identical phi nodes in IR. And matcher is smart enough to find that
new created phi matches both of them. So we try to replace our phi node with
matched ones twice and what is bad we delete our phi node twice causing a crash.

As soon as we found that we have two identical Phi nodes it makes sense to do
a clean-up and replace one phi node by other one.
The patch implements it.

Reviewers: john.brawn, reames
Reviewed By: john.brawn
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D43758

llvm-svn: 327250

2 files changed, 40 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
index 1b1bad1ac93..422a0a972fb 100644
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -2946,8 +2946,20 @@ private:
         Matched.clear();
       }
       if (IsMatched) {
-        // Replace all matched values and erase them.
+        // If we matched phi node to different but identical phis then
+        // make a simplification here.
+        DenseMap<PHINode *, PHINode *> MatchedPHINodeMapping;
         for (auto MV : Matched) {
+          auto AlreadyMatched = MatchedPHINodeMapping.find(MV.first);
+          if (AlreadyMatched != MatchedPHINodeMapping.end()) {
+            MV.second->replaceAllUsesWith(AlreadyMatched->second);
+            ST.Put(MV.second, AlreadyMatched->second);
+            MV.second->eraseFromParent();
+          } else
+            MatchedPHINodeMapping.insert({ MV.first, MV.second });
+        }
+        // Replace all matched values and erase them.
+        for (auto MV : MatchedPHINodeMapping) {
           MV.first->replaceAllUsesWith(MV.second);
           PhiNodesToMatch.erase(MV.first);
           ST.Put(MV.first, MV.second);
diff --git a/llvm/test/Transforms/CodeGenPrepare/X86/sink-addrmode-two-phi.ll b/llvm/test/Transforms/CodeGenPrepare/X86/sink-addrmode-two-phi.ll
new file mode 100644
index 00000000000..817382a07bd
--- /dev/null
+++ b/llvm/test/Transforms/CodeGenPrepare/X86/sink-addrmode-two-phi.ll
@@ -0,0 +1,27 @@
+; RUN: opt -S -codegenprepare -disable-complex-addr-modes=false  %s | FileCheck %s --check-prefix=CHECK
+target datalayout =
+"e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @test() {
+entry:
+  %0 = getelementptr inbounds i64, i64 * null, i64 undef
+  br label %start
+
+start:
+  %val1 = phi i64 * [ %0, %entry ], [ %val4, %exit ]
+  %val2 = phi i64 * [ null, %entry ], [ %val5, %exit ]
+  br i1 false, label %slowpath, label %exit
+
+slowpath:
+  %elem1 = getelementptr inbounds i64, i64 * undef, i64 undef
+  br label %exit
+
+exit:
+; CHECK: sunkaddr
+  %val3 = phi i64 * [ undef, %slowpath ], [ %val2, %start ]
+  %val4 = phi i64 * [ %elem1, %slowpath ], [ %val1, %start ]
+  %val5 = phi i64 * [ undef, %slowpath ], [ %val2, %start ]
+  %loadx = load i64, i64 * %val4, align 8
+  br label %start
+}