[DAGCombiner] Teach SearchForAndLoads to handle an AND with 2 constant operands. #142062
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…t operands. If opaque constants are involved we can have an AND with 2 constant operands that hasn't been simplified. If this is the case, we need to modify at least one of the constants if it is out of range. Fixes llvm#142004
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@llvm/pr-subscribers-llvm-selectiondag Author: Craig Topper (topperc) ChangesIf opaque constants are involved we can have an AND with 2 constant Fixes #142004 Full diff: https://github.com/llvm/llvm-project/pull/142062.diff 2 Files Affected:
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index e05f85ea3bd8e..fe5310aff6c73 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -6812,7 +6812,8 @@ bool DAGCombiner::SearchForAndLoads(SDNode *N,
// Some constants may need fixing up later if they are too large.
if (auto *C = dyn_cast<ConstantSDNode>(Op)) {
- if ((N->getOpcode() == ISD::OR || N->getOpcode() == ISD::XOR) &&
+ if ((N->getOpcode() == ISD::OR || N->getOpcode() == ISD::XOR ||
+ N->getOpcode() == ISD::AND) &&
(Mask->getAPIntValue() & C->getAPIntValue()) != C->getAPIntValue())
NodesWithConsts.insert(N);
continue;
@@ -6927,7 +6928,13 @@ bool DAGCombiner::BackwardsPropagateMask(SDNode *N) {
SDValue Op0 = LogicN->getOperand(0);
SDValue Op1 = LogicN->getOperand(1);
- if (isa<ConstantSDNode>(Op0))
+ // We only need to fix AND if both inputs are constants. And we only need
+ // to fix one of the constants.
+ if (LogicN->getOpcode() == ISD::AND &&
+ (!isa<ConstantSDNode>(Op0) || !isa<ConstantSDNode>(Op1)))
+ continue;
+
+ if (isa<ConstantSDNode>(Op0) && LogicN->getOpcode() != ISD::AND)
Op0 =
DAG.getNode(ISD::AND, SDLoc(Op0), Op0.getValueType(), Op0, MaskOp);
diff --git a/llvm/test/CodeGen/RISCV/pr142004.ll b/llvm/test/CodeGen/RISCV/pr142004.ll
new file mode 100644
index 0000000000000..709644e49e704
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/pr142004.ll
@@ -0,0 +1,33 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc < %s -mtriple=riscv64 | FileCheck %s
+
+@f = global i64 0, align 8
+@d = global i64 0, align 8
+@e = global i32 0, align 8
+
+define i32 @foo(i32 %x) {
+; CHECK-LABEL: foo:
+; CHECK: # %bb.0: # %entry
+; CHECK-NEXT: lui a1, %hi(f)
+; CHECK-NEXT: lui a2, %hi(d)
+; CHECK-NEXT: lbu a1, %lo(f)(a1)
+; CHECK-NEXT: lhu a2, %lo(d)(a2)
+; CHECK-NEXT: slli a0, a0, 48
+; CHECK-NEXT: srli a3, a0, 48
+; CHECK-NEXT: xori a0, a1, 255
+; CHECK-NEXT: or a0, a0, a2
+; CHECK-NEXT: lui a1, %hi(e)
+; CHECK-NEXT: sw a3, %lo(e)(a1)
+; CHECK-NEXT: ret
+entry:
+ %1 = load i64, ptr @f, align 8
+ %conv1 = and i64 %1, 255
+ %conv2 = xor i64 %conv1, 255
+ %2 = load i64, ptr @d, align 8
+ %or = or i64 %conv2, %2
+ %conv3 = trunc i64 %or to i32
+ %conv4 = and i32 %conv3, 65535
+ %and = and i32 %x, 65535
+ store i32 %and, ptr @e
+ ret i32 %conv4
+}
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| if (auto *C = dyn_cast<ConstantSDNode>(Op)) { | ||
| if ((N->getOpcode() == ISD::OR || N->getOpcode() == ISD::XOR) && | ||
| if ((N->getOpcode() == ISD::OR || N->getOpcode() == ISD::XOR || | ||
| N->getOpcode() == ISD::AND) && |
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ISD::isBitwiseLogicOp(N->getOpcode())
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N is always a bitwise op. We can insert an assertion instead.
https://github.com/llvm/llvm-project/blob/2a3afa2feb90844ad0f8b0bc57663e2aec06cd0a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp#L6858-L6864
https://github.com/llvm/llvm-project/blob/2a3afa2feb90844ad0f8b0bc57663e2aec06cd0a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp#L6891-L6906
https://github.com/llvm/llvm-project/blob/2a3afa2feb90844ad0f8b0bc57663e2aec06cd0a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp#L7494-L7501
| if (auto *C = dyn_cast<ConstantSDNode>(Op)) { | ||
| if ((N->getOpcode() == ISD::OR || N->getOpcode() == ISD::XOR) && | ||
| if ((N->getOpcode() == ISD::OR || N->getOpcode() == ISD::XOR || | ||
| N->getOpcode() == ISD::AND) && |
There was a problem hiding this comment.
N is always a bitwise op. We can insert an assertion instead.
https://github.com/llvm/llvm-project/blob/2a3afa2feb90844ad0f8b0bc57663e2aec06cd0a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp#L6858-L6864
https://github.com/llvm/llvm-project/blob/2a3afa2feb90844ad0f8b0bc57663e2aec06cd0a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp#L6891-L6906
https://github.com/llvm/llvm-project/blob/2a3afa2feb90844ad0f8b0bc57663e2aec06cd0a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp#L7494-L7501
4 participants
If opaque constants are involved we can have an AND with 2 constant
operands that hasn't been simplified. If this is the case, we need
to modify at least one of the constants if it is out of range.
Fixes #142004