[PATCH] D85332: [SCCP] Do not replace deref'able ptr with un-deref'able one.

[Florian Hahn via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rG3542feeb2077: [SCCP] Do not replace deref'able ptr with un-deref'able one. (authored by fhahn).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D85332/new/

https://reviews.llvm.org/D85332

Files:
  llvm/lib/Transforms/Scalar/SCCP.cpp
  llvm/test/Transforms/SCCP/apint-bigint2.ll
  llvm/test/Transforms/SCCP/indirectbr.ll
  llvm/test/Transforms/SCCP/replace-dereferenceable-ptr-with-undereferenceable.ll


Index: llvm/test/Transforms/SCCP/replace-dereferenceable-ptr-with-undereferenceable.ll
===================================================================
--- llvm/test/Transforms/SCCP/replace-dereferenceable-ptr-with-undereferenceable.ll
+++ llvm/test/Transforms/SCCP/replace-dereferenceable-ptr-with-undereferenceable.ll
@@ -11,7 +11,7 @@
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32* [[P:%.*]], getelementptr inbounds (i32, i32* getelementptr inbounds ([1 x i32], [1 x i32]* @x, i64 0, i64 0), i64 1)
 ; CHECK-NEXT:    br i1 [[CMP]], label [[IF_THEN:%.*]], label [[IF_END:%.*]]
 ; CHECK:       if.then:
-; CHECK-NEXT:    store i32 2, i32* getelementptr inbounds (i32, i32* getelementptr inbounds ([1 x i32], [1 x i32]* @x, i64 0, i64 0), i64 1), align 4
+; CHECK-NEXT:    store i32 2, i32* [[P]], align 4
 ; CHECK-NEXT:    br label [[IF_END]]
 ; CHECK:       if.end:
 ; CHECK-NEXT:    [[TMP0:%.*]] = load i32, i32* getelementptr inbounds ([1 x i32], [1 x i32]* @y, i64 0, i64 0), align 4
@@ -65,7 +65,7 @@
 ; CHECK-NEXT:    [[CMP_0:%.*]] = icmp eq i32* [[P:%.*]], getelementptr inbounds (i32, i32* getelementptr inbounds ([1 x i32], [1 x i32]* @x, i64 0, i64 0), i64 1)
 ; CHECK-NEXT:    br i1 [[CMP_0]], label [[IF_THEN:%.*]], label [[IF_END:%.*]]
 ; CHECK:       if.then:
-; CHECK-NEXT:    store i32 2, i32* getelementptr inbounds (i32, i32* getelementptr inbounds ([1 x i32], [1 x i32]* @x, i64 0, i64 0), i64 1), align 4
+; CHECK-NEXT:    store i32 2, i32* [[P]], align 4
 ; CHECK-NEXT:    ret i1 true
 ; CHECK:       if.end:
 ; CHECK-NEXT:    [[CMP_2:%.*]] = icmp eq i32* [[P]], getelementptr inbounds (i32, i32* getelementptr inbounds ([1 x i32], [1 x i32]* @x, i64 0, i64 0), i64 1)
Index: llvm/test/Transforms/SCCP/indirectbr.ll
===================================================================
--- llvm/test/Transforms/SCCP/indirectbr.ll
+++ llvm/test/Transforms/SCCP/indirectbr.ll
@@ -31,7 +31,9 @@
 define void @indbrtest2() {
 ; CHECK-LABEL: @indbrtest2(
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    br label [[BB1:%.*]]
+; CHECK-NEXT:    [[B:%.*]] = inttoptr i64 ptrtoint (i8* blockaddress(@indbrtest2, [[BB1:%.*]]) to i64) to i8*
+; CHECK-NEXT:    [[C:%.*]] = bitcast i8* [[B]] to i8*
+; CHECK-NEXT:    br label [[BB1]]
 ; CHECK:       BB1:
 ; CHECK-NEXT:    call void @BB1_f()
 ; CHECK-NEXT:    ret void
Index: llvm/test/Transforms/SCCP/apint-bigint2.ll
===================================================================
--- llvm/test/Transforms/SCCP/apint-bigint2.ll
+++ llvm/test/Transforms/SCCP/apint-bigint2.ll
@@ -51,8 +51,10 @@
 }
 
 ; CHECK-LABEL: @index_too_large
-; CHECK-NEXT: store i101* getelementptr (i101, i101* getelementptr ([6 x i101], [6 x i101]* @Y, i32 0, i32 -1), i101 9224497936761618431), i101** undef
-; CHECK-NEXT: ret void
+; CHECK-NEXT:    %ptr1 = getelementptr [6 x i101], [6 x i101]* @Y, i32 0, i32 -1
+; CHECK-NEXT:    %ptr2 = getelementptr i101, i101* %ptr1, i101 9224497936761618431
+; CHECK-NEXT:    store i101* %ptr2, i101** undef
+; CHECK-NEXT:    ret void
 define void @index_too_large() {
   %ptr1 = getelementptr [6 x i101], [6 x i101]* @Y, i32 0, i32 -1
   %ptr2 = getelementptr i101, i101* %ptr1, i101 9224497936761618431
Index: llvm/lib/Transforms/Scalar/SCCP.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/SCCP.cpp
+++ llvm/lib/Transforms/Scalar/SCCP.cpp
@@ -31,6 +31,7 @@
 #include "llvm/Analysis/DomTreeUpdater.h"
 #include "llvm/Analysis/GlobalsModRef.h"
 #include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Analysis/Loads.h"
 #include "llvm/Analysis/TargetLibraryInfo.h"
 #include "llvm/Analysis/ValueLattice.h"
 #include "llvm/Analysis/ValueLatticeUtils.h"
@@ -177,6 +178,8 @@
   LLVMContext &Ctx;
 
 public:
+  const DataLayout &getDataLayout() const { return DL; }
+
   void addAnalysis(Function &F, AnalysisResultsForFn A) {
     AnalysisResults.insert({&F, std::move(A)});
   }
@@ -1630,6 +1633,14 @@
     return false;
   }
 
+  // Do not propagate equality of a un-dereferenceable pointer.
+  // FIXME: Currently this only treats pointers one past the last element
+  // for array types. Should probably be much stricter.
+  if (Const->getType()->isPointerTy() &&
+      !canReplacePointersIfEqual(V, Const, Solver.getDataLayout(),
+                                 dyn_cast<Instruction>(V)))
+    return false;
+
   LLVM_DEBUG(dbgs() << "  Constant: " << *Const << " = " << *V << '\n');
 
   // Replaces all of the uses of a variable with uses of the constant.


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