From 8e5c298a178c21e115ec086295e29c17b06532ae Mon Sep 17 00:00:00 2001
From: David Majnemer <david.majnemer@gmail.com>
Date: Fri, 8 Aug 2014 05:50:43 +0000
Subject: [PATCH] GlobalOpt: Optimize in the face of insertvalue/extractvalue

GlobalOpt didn't know how to simulate InsertValueInst or
ExtractValueInst.  Optimizing these is pretty straightforward.

N.B. This came up when looking at clang's IRGen for MS ABI member
pointers; they are represented as aggregates.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215184 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/IPO/GlobalOpt.cpp                | 11 +++++++++++
 .../GlobalOpt/constantfold-initializers.ll      | 17 +++++++++++++++--
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/lib/Transforms/IPO/GlobalOpt.cpp b/lib/Transforms/IPO/GlobalOpt.cpp
index c1d0d3bcdb1..06ee5a8257e 100644
--- a/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/lib/Transforms/IPO/GlobalOpt.cpp
@@ -2394,6 +2394,17 @@ bool Evaluator::EvaluateBlock(BasicBlock::iterator CurInst,
                                            getVal(SI->getOperand(2)));
       DEBUG(dbgs() << "Found a Select! Simplifying: " << *InstResult
             << "\n");
+    } else if (auto *EVI = dyn_cast<ExtractValueInst>(CurInst)) {
+      InstResult = ConstantExpr::getExtractValue(
+          getVal(EVI->getAggregateOperand()), EVI->getIndices());
+      DEBUG(dbgs() << "Found an ExtractValueInst! Simplifying: " << *InstResult
+                   << "\n");
+    } else if (auto *IVI = dyn_cast<InsertValueInst>(CurInst)) {
+      InstResult = ConstantExpr::getInsertValue(
+          getVal(IVI->getAggregateOperand()),
+          getVal(IVI->getInsertedValueOperand()), IVI->getIndices());
+      DEBUG(dbgs() << "Found an InsertValueInst! Simplifying: " << *InstResult
+                   << "\n");
     } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(CurInst)) {
       Constant *P = getVal(GEP->getOperand(0));
       SmallVector<Constant*, 8> GEPOps;
diff --git a/test/Transforms/GlobalOpt/constantfold-initializers.ll b/test/Transforms/GlobalOpt/constantfold-initializers.ll
index 4a25d661edc..36de19c1cd8 100644
--- a/test/Transforms/GlobalOpt/constantfold-initializers.ll
+++ b/test/Transforms/GlobalOpt/constantfold-initializers.ll
@@ -81,10 +81,23 @@ entry:
   ret void
 }
 
+@test6_v1 = internal global { i32, i32 } { i32 42, i32 0 }, align 8
+@test6_v2 = global i32 0, align 4
+; CHECK: @test6_v2 = global i32 42, align 4
+define internal void @test6() {
+  %load = load { i32, i32 }* @test6_v1, align 8
+  %xv0 = extractvalue { i32, i32 } %load, 0
+  %iv = insertvalue { i32, i32 } %load, i32 %xv0, 1
+  %xv1 = extractvalue { i32, i32 } %iv, 1
+  store i32 %xv1, i32* @test6_v2, align 4
+  ret void
+}
+
 @llvm.global_ctors = appending constant
-  [5 x { i32, void ()* }]
+  [6 x { i32, void ()* }]
   [{ i32, void ()* } { i32 65535, void ()* @test1 },
    { i32, void ()* } { i32 65535, void ()* @test2 },
    { i32, void ()* } { i32 65535, void ()* @test3 },
    { i32, void ()* } { i32 65535, void ()* @test4 },
-   { i32, void ()* } { i32 65535, void ()* @test5 }]
+   { i32, void ()* } { i32 65535, void ()* @test5 },
+   { i32, void ()* } { i32 65535, void ()* @test6 }]