Restrict somewhat the memory-allocation pointer cmp opt from r223093

Based on review comments from Richard Smith, restrict this optimization from
applying to globals that might resolve lazily to other dynamically-loaded
modules, and also from dynamic allocas (which might be transformed into malloc
calls). In short, take extra care that the compared-to pointer is really
simultaneously live with the memory allocation.

llvm-svn: 223347

2 files changed, 165 insertions, 4 deletions

diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 85ebf694e69..51a295aa5b4 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -2026,12 +2026,22 @@ static Constant *computePointerICmp(const DataLayout *DL,
     };
 
     // Is the set of underlying objects all things which must be disjoint from
-    // noalias calls.
+    // noalias calls. For allocas, we consider only static ones (dynamic
+    // allocas might be transformed into calls to malloc not simultaneously
+    // live with the compared-to allocation). For globals, we exclude symbols
+    // that might be resolve lazily to symbols in another dynamically-loaded
+    // library (and, thus, could be malloc'ed by the implementation).
     auto IsAllocDisjoint = [](SmallVectorImpl<Value *> &Objects) {
       return std::all_of(Objects.begin(), Objects.end(),
                          [](Value *V){
-                           if (isa<AllocaInst>(V) || isa<GlobalValue>(V))
-                             return true;
+                           if (const AllocaInst *AI = dyn_cast<AllocaInst>(V))
+                             return AI->isStaticAlloca();
+                           if (const GlobalValue *GV = dyn_cast<GlobalValue>(V))
+                             return (GV->hasLocalLinkage() ||
+                                     GV->hasHiddenVisibility() ||
+                                     GV->hasProtectedVisibility() ||
+                                     GV->hasUnnamedAddr()) &&
+                                    !GV->isThreadLocal();
                            if (const Argument *A = dyn_cast<Argument>(V))
                              return A->hasByValAttr();
                            return false;
diff --git a/llvm/test/Transforms/InstSimplify/noalias-ptr.ll b/llvm/test/Transforms/InstSimplify/noalias-ptr.ll
index e3435097880..7693e554235 100644
--- a/llvm/test/Transforms/InstSimplify/noalias-ptr.ll
+++ b/llvm/test/Transforms/InstSimplify/noalias-ptr.ll
@@ -3,6 +3,11 @@ target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
 @g1 = global i32 0, align 4
+@g2 = internal global i32 0, align 4
+@g3 = unnamed_addr global i32 0, align 4
+@g4 = hidden global i32 0, align 4
+@g5 = protected global i32 0, align 4
+@g6 = thread_local unnamed_addr global i32 0, align 4
 
 ; Make sure we can simplify away a pointer comparison between
 ; dynamically-allocated memory and a local stack allocation.
@@ -43,7 +48,7 @@ define void @_Z2p2bb(i1 zeroext %b1, i1 zeroext %b2) #0 {
   %mStackData = alloca [10 x i32], align 16
   %1 = bitcast [10 x i32]* %mStackData to i8*
   %2 = getelementptr inbounds [10 x i32]* %mStackData, i64 0, i64 0
-  %3 = select i1 %b1, i32* %2, i32* @g1
+  %3 = select i1 %b1, i32* %2, i32* @g2
   %4 = tail call noalias i8* @_Znam(i64 48) #4
   %5 = tail call noalias i8* @_Znam(i64 48) #4
   %.v = select i1 %b2, i8* %4, i8* %5
@@ -64,6 +69,81 @@ define void @_Z2p2bb(i1 zeroext %b1, i1 zeroext %b2) #0 {
   ret void
 }
 
+define void @_Z2p4bb(i1 zeroext %b1, i1 zeroext %b2) #0 {
+  %mStackData = alloca [10 x i32], align 16
+  %1 = bitcast [10 x i32]* %mStackData to i8*
+  %2 = getelementptr inbounds [10 x i32]* %mStackData, i64 0, i64 0
+  %3 = select i1 %b1, i32* %2, i32* @g3
+  %4 = tail call noalias i8* @_Znam(i64 48) #4
+  %5 = tail call noalias i8* @_Znam(i64 48) #4
+  %.v = select i1 %b2, i8* %4, i8* %5
+  %6 = bitcast i8* %.v to i32*
+  %7 = icmp eq i32* %6, %3
+  br i1 %7, label %9, label %8
+
+; CHECK-LABEL: @_Z2p4bb
+; CHECK-NOT: icmp
+; CHECK: ret void
+
+; <label>:8                                       ; preds = %0
+  call void @_ZdaPv(i8* %4) #5
+  call void @_ZdaPv(i8* %5) #5
+  br label %9
+
+; <label>:9                                       ; preds = %0, %8
+  ret void
+}
+
+define void @_Z2p5bb(i1 zeroext %b1, i1 zeroext %b2) #0 {
+  %mStackData = alloca [10 x i32], align 16
+  %1 = bitcast [10 x i32]* %mStackData to i8*
+  %2 = getelementptr inbounds [10 x i32]* %mStackData, i64 0, i64 0
+  %3 = select i1 %b1, i32* %2, i32* @g4
+  %4 = tail call noalias i8* @_Znam(i64 48) #4
+  %5 = tail call noalias i8* @_Znam(i64 48) #4
+  %.v = select i1 %b2, i8* %4, i8* %5
+  %6 = bitcast i8* %.v to i32*
+  %7 = icmp eq i32* %6, %3
+  br i1 %7, label %9, label %8
+
+; CHECK-LABEL: @_Z2p5bb
+; CHECK-NOT: icmp
+; CHECK: ret void
+
+; <label>:8                                       ; preds = %0
+  call void @_ZdaPv(i8* %4) #5
+  call void @_ZdaPv(i8* %5) #5
+  br label %9
+
+; <label>:9                                       ; preds = %0, %8
+  ret void
+}
+
+define void @_Z2p6bb(i1 zeroext %b1, i1 zeroext %b2) #0 {
+  %mStackData = alloca [10 x i32], align 16
+  %1 = bitcast [10 x i32]* %mStackData to i8*
+  %2 = getelementptr inbounds [10 x i32]* %mStackData, i64 0, i64 0
+  %3 = select i1 %b1, i32* %2, i32* @g5
+  %4 = tail call noalias i8* @_Znam(i64 48) #4
+  %5 = tail call noalias i8* @_Znam(i64 48) #4
+  %.v = select i1 %b2, i8* %4, i8* %5
+  %6 = bitcast i8* %.v to i32*
+  %7 = icmp eq i32* %6, %3
+  br i1 %7, label %9, label %8
+
+; CHECK-LABEL: @_Z2p6bb
+; CHECK-NOT: icmp
+; CHECK: ret void
+
+; <label>:8                                       ; preds = %0
+  call void @_ZdaPv(i8* %4) #5
+  call void @_ZdaPv(i8* %5) #5
+  br label %9
+
+; <label>:9                                       ; preds = %0, %8
+  ret void
+}
+
 ; Here's another case involving multiple underlying objects, but this time we
 ; must keep the comparison (it might involve a regular pointer-typed function
 ; argument).
@@ -93,6 +173,77 @@ define void @_Z4nopebbPi(i1 zeroext %b1, i1 zeroext %b2, i32* readnone %q) #0 {
   ret void
 }
 
+define void @_Z2p3bb(i1 zeroext %b1, i1 zeroext %b2) #0 {
+  %mStackData = alloca [10 x i32], align 16
+  %1 = bitcast [10 x i32]* %mStackData to i8*
+  %2 = getelementptr inbounds [10 x i32]* %mStackData, i64 0, i64 0
+  %3 = select i1 %b1, i32* %2, i32* @g1
+  %4 = tail call noalias i8* @_Znam(i64 48) #4
+  %5 = tail call noalias i8* @_Znam(i64 48) #4
+  %.v = select i1 %b2, i8* %4, i8* %5
+  %6 = bitcast i8* %.v to i32*
+  %7 = icmp eq i32* %6, %3
+  br i1 %7, label %9, label %8
+
+; CHECK-LABEL: @_Z2p3bb
+; CHECK: icmp
+; CHECK: ret void
+
+; <label>:8                                       ; preds = %0
+  call void @_ZdaPv(i8* %4) #5
+  call void @_ZdaPv(i8* %5) #5
+  br label %9
+
+; <label>:9                                       ; preds = %0, %8
+  ret void
+}
+
+define void @_Z2p7bb(i1 zeroext %b1, i1 zeroext %b2) #0 {
+  %mStackData = alloca [10 x i32], align 16
+  %1 = bitcast [10 x i32]* %mStackData to i8*
+  %2 = getelementptr inbounds [10 x i32]* %mStackData, i64 0, i64 0
+  %3 = select i1 %b1, i32* %2, i32* @g6
+  %4 = tail call noalias i8* @_Znam(i64 48) #4
+  %5 = tail call noalias i8* @_Znam(i64 48) #4
+  %.v = select i1 %b2, i8* %4, i8* %5
+  %6 = bitcast i8* %.v to i32*
+  %7 = icmp eq i32* %6, %3
+  br i1 %7, label %9, label %8
+
+; CHECK-LABEL: @_Z2p7bb
+; CHECK: icmp
+; CHECK: ret void
+
+; <label>:8                                       ; preds = %0
+  call void @_ZdaPv(i8* %4) #5
+  call void @_ZdaPv(i8* %5) #5
+  br label %9
+
+; <label>:9                                       ; preds = %0, %8
+  ret void
+}
+
+define void @_Z2p2v(i32 %c) #0 {
+  %mStackData = alloca [10 x i32], i32 %c, align 16
+  %1 = bitcast [10 x i32]* %mStackData to i8*
+  %2 = tail call noalias i8* @_Znam(i64 48) #4
+  %3 = bitcast i8* %2 to i32*
+  %4 = getelementptr inbounds [10 x i32]* %mStackData, i64 0, i64 0
+  %5 = icmp eq i32* %3, %4
+  br i1 %5, label %7, label %6
+
+; CHECK-LABEL: @_Z2p2v
+; CHECK: icmp
+; CHECK: ret void
+
+; <label>:6                                       ; preds = %0
+  call void @_ZdaPv(i8* %2) #5
+  br label %7
+
+; <label>:7                                       ; preds = %0, %6
+  ret void
+}
+
 ; Function Attrs: nobuiltin
 declare noalias i8* @_Znam(i64) #2