Skip to content

S
swiftshader
Commit 24350b8d by Nicolas Capens Committed by Nicolas Capens
Options

Limit the recursion depth of llvm::SelectionDAG::isSplatValue()

This method previously always recursively checked both the left-hand side and right-hand side of binary operations for splatted (broadcast) values to determine if the parent DAG node is a splat. For chained operations, such as the 10,000 adds of the dEQP-VK.spirv_assembly. instruction.graphics.spirv_ids_abuse.lots_ids_frag/vert tests, very deep recursion could result in stack overflow. Like several other SelectionDAG methods, limit the recursion depth to MaxRecursionDepth (6). Bug: b/173785481 Change-Id: I22ee0453db7cf1311267291a331ad8fa3b57b1d9 Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/50672 Presubmit-Ready: Nicolas Capens <nicolascapens@google.com> Reviewed-by: 's avatarJason Macnak <natsu@google.com> Reviewed-by: 's avatarAntonio Maiorano <amaiorano@google.com> Tested-by: 's avatarJason Macnak <natsu@google.com>
parent 88e698a4
Showing with 9 additions and 5 deletions
third_party/llvm-10.0/llvm/include/llvm/CodeGen/SelectionDAG.h
...@@ -1618,7 +1618,8 @@ public: ...@@ -1618,7 +1618,8 @@ public:
/// for \p DemandedElts. /// for \p DemandedElts.
/// ///
/// NOTE: The function will return true for a demanded splat of UNDEF values. /// NOTE: The function will return true for a demanded splat of UNDEF values.
bool isSplatValue(SDValue V, const APInt &DemandedElts, APInt &UndefElts); bool isSplatValue(SDValue V, const APInt &DemandedElts, APInt &UndefElts,
unsigned Depth = 0);
/// Test whether \p V has a splatted value. /// Test whether \p V has a splatted value.
bool isSplatValue(SDValue V, bool AllowUndefs = false); bool isSplatValue(SDValue V, bool AllowUndefs = false);
......
third_party/llvm-10.0/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
...@@ -2278,10 +2278,13 @@ bool SelectionDAG::MaskedValueIsAllOnes(SDValue V, const APInt &Mask, ...@@ -2278,10 +2278,13 @@ bool SelectionDAG::MaskedValueIsAllOnes(SDValue V, const APInt &Mask,
/// isSplatValue - Return true if the vector V has the same value /// isSplatValue - Return true if the vector V has the same value
/// across all DemandedElts. /// across all DemandedElts.
bool SelectionDAG::isSplatValue(SDValue V, const APInt &DemandedElts, bool SelectionDAG::isSplatValue(SDValue V, const APInt &DemandedElts,
APInt &UndefElts) { APInt &UndefElts, unsigned Depth) {
if (!DemandedElts) if (!DemandedElts)
return false; // No demanded elts, better to assume we don't know anything. return false; // No demanded elts, better to assume we don't know anything.
if (Depth >= MaxRecursionDepth)
return false; // Limit search depth.
EVT VT = V.getValueType(); EVT VT = V.getValueType();
assert(VT.isVector() && "Vector type expected"); assert(VT.isVector() && "Vector type expected");
...@@ -2334,7 +2337,7 @@ bool SelectionDAG::isSplatValue(SDValue V, const APInt &DemandedElts, ...@@ -2334,7 +2337,7 @@ bool SelectionDAG::isSplatValue(SDValue V, const APInt &DemandedElts,
uint64_t Idx = SubIdx->getZExtValue(); uint64_t Idx = SubIdx->getZExtValue();
APInt UndefSrcElts; APInt UndefSrcElts;
APInt DemandedSrc = DemandedElts.zextOrSelf(NumSrcElts).shl(Idx); APInt DemandedSrc = DemandedElts.zextOrSelf(NumSrcElts).shl(Idx);
if (isSplatValue(Src, DemandedSrc, UndefSrcElts)) { if (isSplatValue(Src, DemandedSrc, UndefSrcElts, Depth + 1)) {
UndefElts = UndefSrcElts.extractBits(NumElts, Idx); UndefElts = UndefSrcElts.extractBits(NumElts, Idx);
return true; return true;
} }
...@@ -2347,8 +2350,8 @@ bool SelectionDAG::isSplatValue(SDValue V, const APInt &DemandedElts, ...@@ -2347,8 +2350,8 @@ bool SelectionDAG::isSplatValue(SDValue V, const APInt &DemandedElts,
APInt UndefLHS, UndefRHS; APInt UndefLHS, UndefRHS;
SDValue LHS = V.getOperand(0); SDValue LHS = V.getOperand(0);
SDValue RHS = V.getOperand(1); SDValue RHS = V.getOperand(1);
if (isSplatValue(LHS, DemandedElts, UndefLHS) && if (isSplatValue(LHS, DemandedElts, UndefLHS, Depth + 1) &&
isSplatValue(RHS, DemandedElts, UndefRHS)) { isSplatValue(RHS, DemandedElts, UndefRHS, Depth + 1)) {
UndefElts = UndefLHS | UndefRHS; UndefElts = UndefLHS | UndefRHS;
return true; return true;
} }
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment