[PATCH] D76645: [GlobalOpt] Treat null-check of loaded value as use of global (PR35760)

[Vedant Kumar via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rGb7cd291c1542: [GlobalOpt] Treat null-check of loaded value as use of global (PR35760) (authored by vsk).
Herald added a project: LLVM.

Changed prior to commit:
  https://reviews.llvm.org/D76645?vs=252154&id=252223#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D76645/new/

https://reviews.llvm.org/D76645

Files:
  llvm/lib/Transforms/IPO/GlobalOpt.cpp
  llvm/test/Transforms/GlobalOpt/null-check-is-use-pr35760.ll


Index: llvm/test/Transforms/GlobalOpt/null-check-is-use-pr35760.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/GlobalOpt/null-check-is-use-pr35760.ll
@@ -0,0 +1,41 @@
+; RUN: opt -S -globalopt -o - < %s | FileCheck %s
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+ at _ZL3g_i = internal global i32* null, align 8
+ at .str = private unnamed_addr constant [2 x i8] c"0\00", align 1
+ at .str.1 = private unnamed_addr constant [2 x i8] c"1\00", align 1
+
+define dso_local i32 @main() {
+  store i32* null, i32** @_ZL3g_i, align 8
+  call void @_ZL13PutsSomethingv()
+  ret i32 0
+}
+
+; CHECK-LABEL: define {{.*}} @_ZL13PutsSomethingv()
+; CHECK: [[gvLoad:%.*]] = load i32*, i32** @_ZL3g_i
+; CHECK-NEXT: icmp eq i32* [[gvLoad]], null
+define internal void @_ZL13PutsSomethingv() {
+  %1 = load i32*, i32** @_ZL3g_i, align 8
+  %2 = icmp eq i32* %1, null
+  br i1 %2, label %3, label %7
+
+3:                                                ; preds = %0
+  %4 = call noalias i8* @malloc(i64 4) #3
+  %5 = bitcast i8* %4 to i32*
+  store i32* %5, i32** @_ZL3g_i, align 8
+  %6 = call i32 @puts(i8* getelementptr inbounds ([2 x i8], [2 x i8]* @.str, i64 0, i64 0))
+  br label %9
+
+7:                                                ; preds = %0
+  %8 = call i32 @puts(i8* getelementptr inbounds ([2 x i8], [2 x i8]* @.str.1, i64 0, i64 0))
+  br label %9
+
+9:                                                ; preds = %7, %3
+  ret void
+}
+
+declare dso_local noalias i8* @malloc(i64)
+
+declare dso_local i32 @puts(i8* nocapture readonly)
Index: llvm/lib/Transforms/IPO/GlobalOpt.cpp
===================================================================
--- llvm/lib/Transforms/IPO/GlobalOpt.cpp
+++ llvm/lib/Transforms/IPO/GlobalOpt.cpp
@@ -659,9 +659,6 @@
       // checked.
       if (PHIs.insert(PN).second && !AllUsesOfValueWillTrapIfNull(PN, PHIs))
         return false;
-    } else if (isa<ICmpInst>(U) &&
-               isa<ConstantPointerNull>(U->getOperand(1))) {
-      // Ignore icmp X, null
     } else {
       //cerr << "NONTRAPPING USE: " << *U;
       return false;


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