[llvm] r358597 - [LVI][CVP] Constrain values in with.overflow branches
Nikita Popov via llvm-commits
llvm-commits at lists.llvm.org
Wed Apr 17 09:57:42 PDT 2019
Author: nikic
Date: Wed Apr 17 09:57:42 2019
New Revision: 358597
URL: http://llvm.org/viewvc/llvm-project?rev=358597&view=rev
Log:
[LVI][CVP] Constrain values in with.overflow branches
If a branch is conditional on extractvalue(op.with.overflow(%x, C), 1)
then we can constrain the value of %x inside the branch based on
makeGuaranteedNoWrapRegion(). We do this by extending the edge-value
handling in LVI. This allows CVP to then fold comparisons against %x,
as illustrated in the tests.
Differential Revision: https://reviews.llvm.org/D60650
Modified:
llvm/trunk/lib/Analysis/LazyValueInfo.cpp
llvm/trunk/test/Transforms/CorrelatedValuePropagation/overflow_predicate.ll
Modified: llvm/trunk/lib/Analysis/LazyValueInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/LazyValueInfo.cpp?rev=358597&r1=358596&r2=358597&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/LazyValueInfo.cpp (original)
+++ llvm/trunk/lib/Analysis/LazyValueInfo.cpp Wed Apr 17 09:57:42 2019
@@ -1134,6 +1134,28 @@ static ValueLatticeElement getValueFromI
return ValueLatticeElement::getOverdefined();
}
+// Handle conditions of the form
+// extractvalue(op.with.overflow(%x, C), 1).
+static ValueLatticeElement getValueFromOverflowCondition(
+ Value *Val, WithOverflowInst *WO, bool IsTrueDest) {
+ // TODO: This only works with a constant RHS for now. We could also compute
+ // the range of the RHS, but this doesn't fit into the current structure of
+ // the edge value calculation.
+ const APInt *C;
+ if (WO->getLHS() != Val || !match(WO->getRHS(), m_APInt(C)))
+ return ValueLatticeElement::getOverdefined();
+
+ // Calculate the possible values of %x for which no overflow occurs.
+ ConstantRange NWR = ConstantRange::makeGuaranteedNoWrapRegion(
+ WO->getBinaryOp(), ConstantRange(*C), WO->getNoWrapKind());
+
+ // If overflow is false, %x is constrained to NWR. If overflow is true, %x is
+ // constrained to it's inverse (all values that might cause overflow).
+ if (IsTrueDest)
+ NWR = NWR.inverse();
+ return ValueLatticeElement::getRange(NWR);
+}
+
static ValueLatticeElement
getValueFromCondition(Value *Val, Value *Cond, bool isTrueDest,
DenseMap<Value*, ValueLatticeElement> &Visited);
@@ -1144,6 +1166,11 @@ getValueFromConditionImpl(Value *Val, Va
if (ICmpInst *ICI = dyn_cast<ICmpInst>(Cond))
return getValueFromICmpCondition(Val, ICI, isTrueDest);
+ if (auto *EVI = dyn_cast<ExtractValueInst>(Cond))
+ if (auto *WO = dyn_cast<WithOverflowInst>(EVI->getAggregateOperand()))
+ if (EVI->getNumIndices() == 1 && *EVI->idx_begin() == 1)
+ return getValueFromOverflowCondition(Val, WO, isTrueDest);
+
// Handle conditions in the form of (cond1 && cond2), we know that on the
// true dest path both of the conditions hold. Similarly for conditions of
// the form (cond1 || cond2), we know that on the false dest path neither
Modified: llvm/trunk/test/Transforms/CorrelatedValuePropagation/overflow_predicate.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/CorrelatedValuePropagation/overflow_predicate.ll?rev=358597&r1=358596&r2=358597&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/CorrelatedValuePropagation/overflow_predicate.ll (original)
+++ llvm/trunk/test/Transforms/CorrelatedValuePropagation/overflow_predicate.ll Wed Apr 17 09:57:42 2019
@@ -19,8 +19,7 @@ define i1 @uadd_ov_false(i8 %x, i8* %px,
; CHECK: no_overflow:
; CHECK-NEXT: [[C1:%.*]] = icmp ugt i8 [[X]], -102
; CHECK-NEXT: store i1 [[C1]], i1* [[PC:%.*]]
-; CHECK-NEXT: [[C2:%.*]] = icmp ugt i8 [[X]], -101
-; CHECK-NEXT: ret i1 [[C2]]
+; CHECK-NEXT: ret i1 false
; CHECK: trap:
; CHECK-NEXT: call void @llvm.trap()
; CHECK-NEXT: unreachable
@@ -52,8 +51,7 @@ define i1 @uadd_ov_true(i8 %x, i8* %px,
; CHECK: overflow:
; CHECK-NEXT: [[C1:%.*]] = icmp ugt i8 [[X]], -100
; CHECK-NEXT: store i1 [[C1]], i1* [[PC:%.*]]
-; CHECK-NEXT: [[C2:%.*]] = icmp ugt i8 [[X]], -101
-; CHECK-NEXT: ret i1 [[C2]]
+; CHECK-NEXT: ret i1 true
; CHECK: trap:
; CHECK-NEXT: call void @llvm.trap()
; CHECK-NEXT: unreachable
@@ -85,8 +83,7 @@ define i1 @sadd_ov_false(i8 %x, i8* %px,
; CHECK: no_overflow:
; CHECK-NEXT: [[C1:%.*]] = icmp sgt i8 [[X]], 26
; CHECK-NEXT: store i1 [[C1]], i1* [[PC:%.*]]
-; CHECK-NEXT: [[C2:%.*]] = icmp sgt i8 [[X]], 27
-; CHECK-NEXT: ret i1 [[C2]]
+; CHECK-NEXT: ret i1 false
; CHECK: trap:
; CHECK-NEXT: call void @llvm.trap()
; CHECK-NEXT: unreachable
@@ -118,8 +115,7 @@ define i1 @sadd_ov_true(i8 %x, i8* %px,
; CHECK: overflow:
; CHECK-NEXT: [[C1:%.*]] = icmp sgt i8 [[X]], 28
; CHECK-NEXT: store i1 [[C1]], i1* [[PC:%.*]]
-; CHECK-NEXT: [[C2:%.*]] = icmp sgt i8 [[X]], 27
-; CHECK-NEXT: ret i1 [[C2]]
+; CHECK-NEXT: ret i1 true
; CHECK: trap:
; CHECK-NEXT: call void @llvm.trap()
; CHECK-NEXT: unreachable
@@ -151,8 +147,7 @@ define i1 @usub_ov_false(i8 %x, i8* %px,
; CHECK: no_overflow:
; CHECK-NEXT: [[C1:%.*]] = icmp ult i8 [[X]], 101
; CHECK-NEXT: store i1 [[C1]], i1* [[PC:%.*]]
-; CHECK-NEXT: [[C2:%.*]] = icmp ult i8 [[X]], 100
-; CHECK-NEXT: ret i1 [[C2]]
+; CHECK-NEXT: ret i1 false
; CHECK: trap:
; CHECK-NEXT: call void @llvm.trap()
; CHECK-NEXT: unreachable
@@ -184,8 +179,7 @@ define i1 @usub_ov_true(i8 %x, i8* %px,
; CHECK: overflow:
; CHECK-NEXT: [[C1:%.*]] = icmp ult i8 [[X]], 99
; CHECK-NEXT: store i1 [[C1]], i1* [[PC:%.*]]
-; CHECK-NEXT: [[C2:%.*]] = icmp ult i8 [[X]], 100
-; CHECK-NEXT: ret i1 [[C2]]
+; CHECK-NEXT: ret i1 true
; CHECK: trap:
; CHECK-NEXT: call void @llvm.trap()
; CHECK-NEXT: unreachable
@@ -217,8 +211,7 @@ define i1 @ssub_ov_false(i8 %x, i8* %px,
; CHECK: no_overflow:
; CHECK-NEXT: [[C1:%.*]] = icmp slt i8 [[X]], -27
; CHECK-NEXT: store i1 [[C1]], i1* [[PC:%.*]]
-; CHECK-NEXT: [[C2:%.*]] = icmp slt i8 [[X]], -28
-; CHECK-NEXT: ret i1 [[C2]]
+; CHECK-NEXT: ret i1 false
; CHECK: trap:
; CHECK-NEXT: call void @llvm.trap()
; CHECK-NEXT: unreachable
@@ -250,8 +243,7 @@ define i1 @ssub_ov_true(i8 %x, i8* %px,
; CHECK: overflow:
; CHECK-NEXT: [[C1:%.*]] = icmp slt i8 [[X]], -29
; CHECK-NEXT: store i1 [[C1]], i1* [[PC:%.*]]
-; CHECK-NEXT: [[C2:%.*]] = icmp slt i8 [[X]], -28
-; CHECK-NEXT: ret i1 [[C2]]
+; CHECK-NEXT: ret i1 true
; CHECK: trap:
; CHECK-NEXT: call void @llvm.trap()
; CHECK-NEXT: unreachable
@@ -283,8 +275,7 @@ define i1 @umul_ov_false(i8 %x, i8* %px,
; CHECK: no_overflow:
; CHECK-NEXT: [[C1:%.*]] = icmp ugt i8 [[X]], 24
; CHECK-NEXT: store i1 [[C1]], i1* [[PC:%.*]]
-; CHECK-NEXT: [[C2:%.*]] = icmp ugt i8 [[X]], 25
-; CHECK-NEXT: ret i1 [[C2]]
+; CHECK-NEXT: ret i1 false
; CHECK: trap:
; CHECK-NEXT: call void @llvm.trap()
; CHECK-NEXT: unreachable
@@ -316,8 +307,7 @@ define i1 @umul_ov_true(i8 %x, i8* %px,
; CHECK: overflow:
; CHECK-NEXT: [[C1:%.*]] = icmp ugt i8 [[X]], 26
; CHECK-NEXT: store i1 [[C1]], i1* [[PC:%.*]]
-; CHECK-NEXT: [[C2:%.*]] = icmp ugt i8 [[X]], 25
-; CHECK-NEXT: ret i1 [[C2]]
+; CHECK-NEXT: ret i1 true
; CHECK: trap:
; CHECK-NEXT: call void @llvm.trap()
; CHECK-NEXT: unreachable
@@ -350,8 +340,7 @@ define i1 @smul_ov_false_bound1(i8 %x, i
; CHECK: no_overflow:
; CHECK-NEXT: [[C1:%.*]] = icmp slt i8 [[X]], -11
; CHECK-NEXT: store i1 [[C1]], i1* [[PC:%.*]]
-; CHECK-NEXT: [[C2:%.*]] = icmp slt i8 [[X]], -12
-; CHECK-NEXT: ret i1 [[C2]]
+; CHECK-NEXT: ret i1 false
; CHECK: trap:
; CHECK-NEXT: call void @llvm.trap()
; CHECK-NEXT: unreachable
@@ -383,8 +372,7 @@ define i1 @smul_ov_false_bound2(i8 %x, i
; CHECK: no_overflow:
; CHECK-NEXT: [[C1:%.*]] = icmp sgt i8 [[X]], 11
; CHECK-NEXT: store i1 [[C1]], i1* [[PC:%.*]]
-; CHECK-NEXT: [[C2:%.*]] = icmp sgt i8 [[X]], 12
-; CHECK-NEXT: ret i1 [[C2]]
+; CHECK-NEXT: ret i1 false
; CHECK: trap:
; CHECK-NEXT: call void @llvm.trap()
; CHECK-NEXT: unreachable
@@ -417,8 +405,7 @@ define i1 @smul_ov_true_bound1(i8 %x, i8
; CHECK: overflow:
; CHECK-NEXT: [[C1:%.*]] = icmp eq i8 [[X]], -13
; CHECK-NEXT: store i1 [[C1]], i1* [[PC:%.*]]
-; CHECK-NEXT: [[C2:%.*]] = icmp eq i8 [[X]], -12
-; CHECK-NEXT: ret i1 [[C2]]
+; CHECK-NEXT: ret i1 false
; CHECK: trap:
; CHECK-NEXT: call void @llvm.trap()
; CHECK-NEXT: unreachable
@@ -450,8 +437,7 @@ define i1 @smul_ov_true_bound2(i8 %x, i8
; CHECK: overflow:
; CHECK-NEXT: [[C1:%.*]] = icmp eq i8 [[X]], 13
; CHECK-NEXT: store i1 [[C1]], i1* [[PC:%.*]]
-; CHECK-NEXT: [[C2:%.*]] = icmp eq i8 [[X]], 12
-; CHECK-NEXT: ret i1 [[C2]]
+; CHECK-NEXT: ret i1 false
; CHECK: trap:
; CHECK-NEXT: call void @llvm.trap()
; CHECK-NEXT: unreachable
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