[llvm] 469debe - [ValueTracking] Support select in findAllocaForValue

[Vitaly Buka via llvm-commits]

Author: Vitaly Buka
Date: 2020-08-27T02:13:52-07:00
New Revision: 469debe0275b5800a2231ae670d235a83e6fbb27

URL: https://github.com/llvm/llvm-project/commit/469debe0275b5800a2231ae670d235a83e6fbb27
DIFF: https://github.com/llvm/llvm-project/commit/469debe0275b5800a2231ae670d235a83e6fbb27.diff

LOG: [ValueTracking] Support select in findAllocaForValue

Added: 
    

Modified: 
    llvm/lib/Analysis/ValueTracking.cpp
    llvm/unittests/Analysis/ValueTrackingTest.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 36998cd90697..5be566b693f4 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -4345,7 +4345,14 @@ findAllocaForValue(Value *V, DenseMap<Value *, AllocaInst *> &AllocaForValue) {
   AllocaInst *Res = nullptr;
   if (CastInst *CI = dyn_cast<CastInst>(V))
     Res = findAllocaForValue(CI->getOperand(0), AllocaForValue);
-  else if (PHINode *PN = dyn_cast<PHINode>(V)) {
+  else if (auto *SI = dyn_cast<SelectInst>(V)) {
+    Res = findAllocaForValue(SI->getTrueValue(), AllocaForValue);
+    if (!Res)
+      return nullptr;
+    AllocaInst *F = findAllocaForValue(SI->getFalseValue(), AllocaForValue);
+    if (F != Res)
+      return nullptr;
+  } else if (PHINode *PN = dyn_cast<PHINode>(V)) {
     for (Value *IncValue : PN->incoming_values()) {
       // Allow self-referencing phi-nodes.
       if (IncValue == PN)

diff  --git a/llvm/unittests/Analysis/ValueTrackingTest.cpp b/llvm/unittests/Analysis/ValueTrackingTest.cpp
index 732f71e4de90..7951d6dec1f8 100644
--- a/llvm/unittests/Analysis/ValueTrackingTest.cpp
+++ b/llvm/unittests/Analysis/ValueTrackingTest.cpp
@@ -1469,6 +1469,23 @@ const std::pair<const char *, bool> FindAllocaForValueTests[] = {
       })",
      true},
 
+    {R"(
+      define void @test(i1 %cond) {
+        %a = alloca i32
+        %r = select i1 %cond, i32* %a, i32* %a
+        ret void
+      })",
+     true},
+
+    {R"(
+      define void @test(i1 %cond) {
+        %a = alloca i32
+        %b = alloca i32
+        %r = select i1 %cond, i32* %a, i32* %b
+        ret void
+      })",
+     false},
+
     {R"(
       define void @test(i1 %cond) {
       entry: