[PATCH] D130211: [GlobalOpt] Enable evaluation of atomic loads

[Alexander Shaposhnikov via Phabricator via llvm-commits]

alexander-shaposhnikov created this revision.
alexander-shaposhnikov added reviewers: rnk, aeubanks, nikic.
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Relax the check to allow evaluation of atomic loads (but still skip volatile loads).

Test plan:
1/ ninja check-llvm check-clang
2/ Bootstrapped Clang/LLVM tests


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D130211

Files:
  llvm/lib/Transforms/Utils/Evaluator.cpp
  llvm/test/Transforms/GlobalOpt/ctor-list-opt.ll


Index: llvm/test/Transforms/GlobalOpt/ctor-list-opt.ll
===================================================================
--- llvm/test/Transforms/GlobalOpt/ctor-list-opt.ll
+++ llvm/test/Transforms/GlobalOpt/ctor-list-opt.ll
@@ -1,7 +1,7 @@
 ; RUN: opt < %s -passes=globalopt -S | FileCheck %s
 ; CHECK-NOT: CTOR
 %ini = type { i32, void()*, i8* }
- at llvm.global_ctors = appending global [15 x %ini] [
+ at llvm.global_ctors = appending global [16 x %ini] [
 	%ini { i32 65534, void ()* @CTOR1, i8* null },
 	%ini { i32 65535, void ()* @CTOR1, i8* null },
 	%ini { i32 65535, void ()* @CTOR1, i8* null },
@@ -13,6 +13,7 @@
 	%ini { i32 65535, void ()* @CTOR7, i8* null },
 	%ini { i32 65535, void ()* @CTOR8, i8* null },
 	%ini { i32 65535, void ()* @CTOR9, i8* null },
+	%ini { i32 65535, void ()* @CTOR14,i8* null },
 	%ini { i32 65536, void ()* @CTOR10_EXTERNAL, i8* null },
 	%ini { i32 65536, void ()* @CTOR11, i8* null },
 	%ini { i32 65537, void ()* @CTOR12, i8* null },
@@ -28,6 +29,7 @@
 @D = global double 0.000000e+00		; <double*> [#uses=1]
 @CTORGV = internal global i1 false		; <i1*> [#uses=2]
 @GA = global i32 0		; <i32*> [#uses=1]
+ at GA14 = global i32 0		; <i32*> [#uses=1]
 
 define internal void @CTOR1() {
 	ret void
@@ -137,3 +139,12 @@
   store atomic i32 123, i32* @GA seq_cst, align 4
   ret void
 }
+
+; CHECK-NOT: CTOR14
+define internal void @CTOR14() {
+  %X = load atomic i32, i32* @GA14 seq_cst, align 4
+  %Y = add i32 %X, 124
+  store i32 %Y, i32* @GA14
+  ret void
+}
+
Index: llvm/lib/Transforms/Utils/Evaluator.cpp
===================================================================
--- llvm/lib/Transforms/Utils/Evaluator.cpp
+++ llvm/lib/Transforms/Utils/Evaluator.cpp
@@ -337,10 +337,10 @@
       if (!Res.first->second.write(Val, Offset, DL))
         return false;
     } else if (LoadInst *LI = dyn_cast<LoadInst>(CurInst)) {
-      if (!LI->isSimple()) {
+      if (LI->isVolatile()) {
         LLVM_DEBUG(
-            dbgs() << "Found a Load! Not a simple load, can not evaluate.\n");
-        return false;  // no volatile/atomic accesses.
+            dbgs() << "Found a Load! Volatile load, can not evaluate.\n");
+        return false;  // no volatile accesses.
       }
 
       Constant *Ptr = getVal(LI->getOperand(0));


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