Revert "r223364 - Revert r223347 which has caused crashes on bootstrap bots."

Reapply r223347, with a fix to not crash on uninserted instructions (or more
precisely, instructions in uninserted blocks). bugpoint was able to reduce the
test case somewhat, but it is still somewhat large (and relies on setting
things up to be simplified during inlining), so I've not included it here.
Nevertheless, it is clear what is going on and why.

Original commit message:

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: 223371

diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 85ebf69..45290fd 100644 (file)
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -2026,12 +2026,23 @@ 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->getParent() && AI->getParent()->getParent() &&
+                                    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 e343509..7693e55 100644 (file)
--- 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