[llvm] r327250 - [CGP] Fix the remove of matched phis in complex addressing mode

Serguei Katkov via llvm-commits llvm-commits at lists.llvm.org
Sun Mar 11 20:50:07 PDT 2018


Author: skatkov
Date: Sun Mar 11 20:50:07 2018
New Revision: 327250

URL: http://llvm.org/viewvc/llvm-project?rev=327250&view=rev
Log:
[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

Added:
    llvm/trunk/test/Transforms/CodeGenPrepare/X86/sink-addrmode-two-phi.ll
Modified:
    llvm/trunk/lib/CodeGen/CodeGenPrepare.cpp

Modified: llvm/trunk/lib/CodeGen/CodeGenPrepare.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/CodeGenPrepare.cpp?rev=327250&r1=327249&r2=327250&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/CodeGenPrepare.cpp (original)
+++ llvm/trunk/lib/CodeGen/CodeGenPrepare.cpp Sun Mar 11 20:50:07 2018
@@ -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);

Added: llvm/trunk/test/Transforms/CodeGenPrepare/X86/sink-addrmode-two-phi.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/CodeGenPrepare/X86/sink-addrmode-two-phi.ll?rev=327250&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/CodeGenPrepare/X86/sink-addrmode-two-phi.ll (added)
+++ llvm/trunk/test/Transforms/CodeGenPrepare/X86/sink-addrmode-two-phi.ll Sun Mar 11 20:50:07 2018
@@ -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
+}




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