[llvm] r344327 - SCCP: avoid caching DenseMap entry that might be invalidated.

[Tim Northover via llvm-commits]

Author: tnorthover
Date: Fri Oct 12 02:01:59 2018
New Revision: 344327

URL: http://llvm.org/viewvc/llvm-project?rev=344327&view=rev
Log:
SCCP: avoid caching DenseMap entry that might be invalidated.

Later calls to getValueState might insert entries into the ValueState map and
cause reallocation, invalidating a reference.

Added:
    llvm/trunk/test/Transforms/SCCP/latticeval-invalidate.ll
Modified:
    llvm/trunk/lib/Transforms/Scalar/SCCP.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/SCCP.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/SCCP.cpp?rev=344327&r1=344326&r2=344327&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/SCCP.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/SCCP.cpp Fri Oct 12 02:01:59 2018
@@ -1017,8 +1017,9 @@ void SCCPSolver::visitBinaryOperator(Ins
 
 // Handle ICmpInst instruction.
 void SCCPSolver::visitCmpInst(CmpInst &I) {
-  LatticeVal &IV = ValueState[&I];
-  if (IV.isOverdefined()) return;
+  // Do not cache this lookup, getValueState calls later in the function might
+  // invalidate the reference.
+  if (ValueState[&I].isOverdefined()) return;
 
   Value *Op1 = I.getOperand(0);
   Value *Op2 = I.getOperand(1);
@@ -1046,7 +1047,8 @@ void SCCPSolver::visitCmpInst(CmpInst &I
   }
 
   // If operands are still unknown, wait for it to resolve.
-  if (!V1State.isOverdefined() && !V2State.isOverdefined() && !IV.isConstant())
+  if (!V1State.isOverdefined() && !V2State.isOverdefined() &&
+      !ValueState[&I].isConstant())
     return;
 
   markOverdefined(&I);

Added: llvm/trunk/test/Transforms/SCCP/latticeval-invalidate.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SCCP/latticeval-invalidate.ll?rev=344327&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/SCCP/latticeval-invalidate.ll (added)
+++ llvm/trunk/test/Transforms/SCCP/latticeval-invalidate.ll Fri Oct 12 02:01:59 2018
@@ -0,0 +1,41 @@
+; RUN: opt -S -sccp %s
+
+ at A = external constant i32
+
+define void @test1() {
+BB4:
+  %A20 = alloca i1
+  %A15 = alloca i64
+  %A7 = alloca i64
+  %A3 = alloca i32**
+  %P = getelementptr i32, i32* @A, i32 0
+  %B = ptrtoint i32* %P to i64
+  %B8 = shl i64 %B, 9223372036854775807
+  %G10 = getelementptr i32*, i32** undef, i64 %B
+  %B10 = urem i64 %B, %B8
+  %B12 = shl i64 %B, %B
+  %BB = and i64 %B, %B8
+  %B1 = xor i64 %B, %B
+  %B23 = lshr i64 %B8, undef
+  %C5 = icmp uge i64 %B, %B10
+  %C17 = fcmp ord double 4.940660e-324, 0x7FEFFFFFFFFFFFFF
+  %C2 = icmp uge i1 %C17, false
+  %G = getelementptr i32, i32* %P, i1 %C17
+  %X = select i1 false, i712 0, i712 1
+  %C4 = icmp ule i1 true, false
+  %B3 = xor i1 %C17, %C2
+  %C33 = icmp slt i1 false, %C5
+  %B15 = sub i64 %B8, %B23
+  %C18 = icmp slt i64 undef, %BB
+  %G29 = getelementptr i32**, i32*** undef, i64 %B15
+  %C35 = icmp eq i1 %C17, undef
+  %C31 = icmp ult i1 %C35, %C5
+  %C29 = icmp sle i1 true, %C5
+  %C16 = icmp ne i16 -1, -32768
+  %A24 = alloca i1
+  %A21 = alloca i1
+  %A25 = alloca i32**
+  %C7 = icmp ule i1 %C4, %B3
+  %C14 = icmp slt i64 %B8, 0
+  ret void
+}