[llvm] eaa1b05 - [LVI] Thread binop over select with constant arms (#110212)
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Sun Dec 8 20:56:22 PST 2024
Author: Yingwei Zheng
Date: 2024-12-09T12:56:19+08:00
New Revision: eaa1b05c48c88ed6da6b8fc21d07f8417575a051
URL: https://github.com/llvm/llvm-project/commit/eaa1b05c48c88ed6da6b8fc21d07f8417575a051
DIFF: https://github.com/llvm/llvm-project/commit/eaa1b05c48c88ed6da6b8fc21d07f8417575a051.diff
LOG: [LVI] Thread binop over select with constant arms (#110212)
Motivating case from https://github.com/delta-io/delta-rs:
https://alive2.llvm.org/ce/z/3mzr4C
Added:
Modified:
llvm/lib/Analysis/LazyValueInfo.cpp
llvm/test/Transforms/CorrelatedValuePropagation/cond-at-use.ll
Removed:
################################################################################
diff --git a/llvm/lib/Analysis/LazyValueInfo.cpp b/llvm/lib/Analysis/LazyValueInfo.cpp
index c9849b86b664c8..349a0a1a2d3c42 100644
--- a/llvm/lib/Analysis/LazyValueInfo.cpp
+++ b/llvm/lib/Analysis/LazyValueInfo.cpp
@@ -924,18 +924,65 @@ LazyValueInfoImpl::solveBlockValueBinaryOpImpl(
Instruction *I, BasicBlock *BB,
std::function<ConstantRange(const ConstantRange &, const ConstantRange &)>
OpFn) {
+ Value *LHS = I->getOperand(0);
+ Value *RHS = I->getOperand(1);
+
+ auto ThreadBinOpOverSelect =
+ [&](Value *X, const ConstantRange &CRX, SelectInst *Y,
+ bool XIsLHS) -> std::optional<ValueLatticeElement> {
+ Value *Cond = Y->getCondition();
+ // Only handle selects with constant values.
+ Constant *TrueC = dyn_cast<Constant>(Y->getTrueValue());
+ if (!TrueC)
+ return std::nullopt;
+ Constant *FalseC = dyn_cast<Constant>(Y->getFalseValue());
+ if (!FalseC)
+ return std::nullopt;
+ if (!isGuaranteedNotToBeUndef(Cond, AC))
+ return std::nullopt;
+
+ ConstantRange TrueX =
+ CRX.intersectWith(getValueFromCondition(X, Cond, /*CondIsTrue=*/true,
+ /*UseBlockValue=*/false)
+ ->asConstantRange(X->getType()));
+ ConstantRange FalseX =
+ CRX.intersectWith(getValueFromCondition(X, Cond, /*CondIsTrue=*/false,
+ /*UseBlockValue=*/false)
+ ->asConstantRange(X->getType()));
+ ConstantRange TrueY = TrueC->toConstantRange();
+ ConstantRange FalseY = FalseC->toConstantRange();
+
+ if (XIsLHS)
+ return ValueLatticeElement::getRange(
+ OpFn(TrueX, TrueY).unionWith(OpFn(FalseX, FalseY)));
+ return ValueLatticeElement::getRange(
+ OpFn(TrueY, TrueX).unionWith(OpFn(FalseY, FalseX)));
+ };
+
// Figure out the ranges of the operands. If that fails, use a
// conservative range, but apply the transfer rule anyways. This
// lets us pick up facts from expressions like "and i32 (call i32
// @foo()), 32"
- std::optional<ConstantRange> LHSRes = getRangeFor(I->getOperand(0), I, BB);
+ std::optional<ConstantRange> LHSRes = getRangeFor(LHS, I, BB);
if (!LHSRes)
return std::nullopt;
- std::optional<ConstantRange> RHSRes = getRangeFor(I->getOperand(1), I, BB);
+ // Try to thread binop over rhs select
+ if (auto *SI = dyn_cast<SelectInst>(RHS)) {
+ if (auto Res = ThreadBinOpOverSelect(LHS, *LHSRes, SI, /*XIsLHS=*/true))
+ return *Res;
+ }
+
+ std::optional<ConstantRange> RHSRes = getRangeFor(RHS, I, BB);
if (!RHSRes)
return std::nullopt;
+ // Try to thread binop over lhs select
+ if (auto *SI = dyn_cast<SelectInst>(LHS)) {
+ if (auto Res = ThreadBinOpOverSelect(RHS, *RHSRes, SI, /*XIsLHS=*/false))
+ return *Res;
+ }
+
const ConstantRange &LHSRange = *LHSRes;
const ConstantRange &RHSRange = *RHSRes;
return ValueLatticeElement::getRange(OpFn(LHSRange, RHSRange));
diff --git a/llvm/test/Transforms/CorrelatedValuePropagation/cond-at-use.ll b/llvm/test/Transforms/CorrelatedValuePropagation/cond-at-use.ll
index 3af4c70a5621c8..cca648bb6ea23e 100644
--- a/llvm/test/Transforms/CorrelatedValuePropagation/cond-at-use.ll
+++ b/llvm/test/Transforms/CorrelatedValuePropagation/cond-at-use.ll
@@ -630,3 +630,95 @@ define i64 @test_shl_nsw_at_use(i64 noundef %x) {
%res = select i1 %cmp, i64 %shr, i64 0
ret i64 %res
}
+
+define i1 @test_icmp_mod(i64 noundef %x) {
+; CHECK-LABEL: @test_icmp_mod(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[REM:%.*]] = srem i64 [[X:%.*]], 86400
+; CHECK-NEXT: [[CMP:%.*]] = icmp slt i64 [[REM]], 0
+; CHECK-NEXT: [[COND:%.*]] = select i1 [[CMP]], i64 86400, i64 0
+; CHECK-NEXT: [[ADD:%.*]] = add nsw i64 [[COND]], [[REM]]
+; CHECK-NEXT: ret i1 false
+;
+entry:
+ %rem = srem i64 %x, 86400
+ %cmp = icmp slt i64 %rem, 0
+ %cond = select i1 %cmp, i64 86400, i64 0
+ %add = add nsw i64 %cond, %rem
+ %cmp1 = icmp ugt i64 %add, 86399
+ ret i1 %cmp1
+}
+
+define i1 @test_icmp_mod_commuted1(i64 noundef %x) {
+; CHECK-LABEL: @test_icmp_mod_commuted1(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[REM:%.*]] = srem i64 [[X:%.*]], 86400
+; CHECK-NEXT: [[CMP:%.*]] = icmp slt i64 [[REM]], 0
+; CHECK-NEXT: [[COND:%.*]] = select i1 [[CMP]], i64 86400, i64 0
+; CHECK-NEXT: [[ADD:%.*]] = add nsw i64 [[REM]], [[COND]]
+; CHECK-NEXT: ret i1 false
+;
+entry:
+ %rem = srem i64 %x, 86400
+ %cmp = icmp slt i64 %rem, 0
+ %cond = select i1 %cmp, i64 86400, i64 0
+ %add = add nsw i64 %rem, %cond
+ %cmp1 = icmp ugt i64 %add, 86399
+ ret i1 %cmp1
+}
+
+define i1 @test_icmp_mod_commuted2(i64 noundef %x) {
+; CHECK-LABEL: @test_icmp_mod_commuted2(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[REM:%.*]] = srem i64 [[X:%.*]], 86400
+; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i64 [[REM]], -1
+; CHECK-NEXT: [[COND:%.*]] = select i1 [[CMP]], i64 0, i64 86400
+; CHECK-NEXT: [[ADD:%.*]] = add nsw i64 [[COND]], [[REM]]
+; CHECK-NEXT: ret i1 false
+;
+entry:
+ %rem = srem i64 %x, 86400
+ %cmp = icmp sgt i64 %rem, -1
+ %cond = select i1 %cmp, i64 0, i64 86400
+ %add = add nsw i64 %cond, %rem
+ %cmp1 = icmp ugt i64 %add, 86399
+ ret i1 %cmp1
+}
+
+define i1 @test_icmp_mod_undef(i64 %x) {
+; CHECK-LABEL: @test_icmp_mod_undef(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[REM:%.*]] = srem i64 [[X:%.*]], 86400
+; CHECK-NEXT: [[CMP:%.*]] = icmp slt i64 [[REM]], 0
+; CHECK-NEXT: [[COND:%.*]] = select i1 [[CMP]], i64 86400, i64 0
+; CHECK-NEXT: [[ADD:%.*]] = add nsw i64 [[COND]], [[REM]]
+; CHECK-NEXT: [[CMP1:%.*]] = icmp ugt i64 [[ADD]], 86399
+; CHECK-NEXT: ret i1 [[CMP1]]
+;
+entry:
+ %rem = srem i64 %x, 86400
+ %cmp = icmp slt i64 %rem, 0
+ %cond = select i1 %cmp, i64 86400, i64 0
+ %add = add nsw i64 %cond, %rem
+ %cmp1 = icmp ugt i64 %add, 86399
+ ret i1 %cmp1
+}
+
+define i1 @test_icmp_mod_wrong_range(i64 noundef %x) {
+; CHECK-LABEL: @test_icmp_mod_wrong_range(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[REM:%.*]] = srem i64 [[X:%.*]], 86400
+; CHECK-NEXT: [[CMP:%.*]] = icmp slt i64 [[REM]], 0
+; CHECK-NEXT: [[COND:%.*]] = select i1 [[CMP]], i64 86401, i64 0
+; CHECK-NEXT: [[ADD:%.*]] = add nsw i64 [[COND]], [[REM]]
+; CHECK-NEXT: [[CMP1:%.*]] = icmp samesign ugt i64 [[ADD]], 86399
+; CHECK-NEXT: ret i1 [[CMP1]]
+;
+entry:
+ %rem = srem i64 %x, 86400
+ %cmp = icmp slt i64 %rem, 0
+ %cond = select i1 %cmp, i64 86401, i64 0
+ %add = add nsw i64 %cond, %rem
+ %cmp1 = icmp ugt i64 %add, 86399
+ ret i1 %cmp1
+}
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