[PATCH] D152145: [InstSimplify] Fold all global variables with initializers

[Anshil Gandhi via Phabricator via llvm-commits]

gandhi21299 updated this revision to Diff 529039.
gandhi21299 added a comment.

- Requested changes

I am not sure how to implement a test with `EvalMode != Min`.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D152145/new/

https://reviews.llvm.org/D152145

Files:
  llvm/lib/Analysis/MemoryBuiltins.cpp
  llvm/test/Transforms/InstSimplify/gv-alloca-cmp.ll


Index: llvm/test/Transforms/InstSimplify/gv-alloca-cmp.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/InstSimplify/gv-alloca-cmp.ll
@@ -0,0 +1,46 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 2
+; RUN: opt < %s -passes=instsimplify -S | FileCheck %s
+
+ at gv = global i64 zeroinitializer, align 16
+
+define i1 @cmp_gv_alloca() {
+; CHECK-LABEL: define i1 @cmp_gv_alloca() {
+; CHECK-NEXT:    ret i1 false
+;
+  %alloca = alloca i64, align 8
+  %cmp = icmp eq ptr %alloca, @gv
+  ret i1 %cmp
+}
+
+ at gv_externally_init = externally_initialized global i64 zeroinitializer, align 16
+
+define i1 @cmp_gv_alloca_extern_init() {
+; CHECK-LABEL: define i1 @cmp_gv_alloca_extern_init() {
+; CHECK-NEXT:    ret i1 false
+;
+  %alloca = alloca i64, align 8
+  %cmp = icmp eq ptr %alloca, @gv_externally_init
+  ret i1 %cmp
+}
+
+ at const_gv = protected addrspace(4) externally_initialized global [4096 x i64] zeroinitializer, align 16
+define i1 @cmp_gv_alloca_cast() {
+; CHECK-LABEL: define i1 @cmp_gv_alloca_cast() {
+; CHECK-NEXT:    ret i1 false
+;
+  %alloca = alloca i64, align 8, addrspace(5)
+  %cast.alloca = addrspacecast ptr addrspace(5) %alloca to ptr
+  %cmp = icmp eq ptr %cast.alloca, addrspacecast (ptr addrspace(4) @const_gv to ptr)
+  ret i1 %cmp
+}
+
+ at gv_weak = weak global i64 zeroinitializer, align 16
+
+define i1 @cmp_gv_weak_alloca() {
+; CHECK-LABEL: define i1 @cmp_gv_weak_alloca() {
+; CHECK-NEXT:    ret i1 false
+;
+  %alloca = alloca i64, align 8
+  %cmp = icmp eq ptr %alloca, @gv_weak
+  ret i1 %cmp
+}
Index: llvm/lib/Analysis/MemoryBuiltins.cpp
===================================================================
--- llvm/lib/Analysis/MemoryBuiltins.cpp
+++ llvm/lib/Analysis/MemoryBuiltins.cpp
@@ -826,7 +826,11 @@
 }
 
 SizeOffsetType ObjectSizeOffsetVisitor::visitGlobalVariable(GlobalVariable &GV){
-  if (!GV.hasDefinitiveInitializer())
+  if ((!GV.hasInitializer() || GV.isInterposable()) &&
+      Options.EvalMode != ObjectSizeOpts::Mode::Min)
+    return unknown();
+
+  if (GV.hasExternalWeakLinkage() && Options.NullIsUnknownSize)
     return unknown();
 
   APInt Size(IntTyBits, DL.getTypeAllocSize(GV.getValueType()));


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