[LVI] Infer non-zero from equality icmp #112838
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@llvm/pr-subscribers-llvm-transforms Author: Yingwei Zheng (dtcxzyw) ChangesThis following pattern is common in loop headers: As Addresses regression introduced by #112742. Full diff: https://github.com/llvm/llvm-project/pull/112838.diff 2 Files Affected:
diff --git a/llvm/lib/Analysis/LazyValueInfo.cpp b/llvm/lib/Analysis/LazyValueInfo.cpp
index 10ad4708596cb3..f29777a584772d 100644
--- a/llvm/lib/Analysis/LazyValueInfo.cpp
+++ b/llvm/lib/Analysis/LazyValueInfo.cpp
@@ -1127,6 +1127,20 @@ std::optional<ValueLatticeElement> LazyValueInfoImpl::getValueFromICmpCondition(
if (!Ty->isIntegerTy())
return ValueLatticeElement::getOverdefined();
+ // a - b or ptrtoint(a) - ptrtoint(b) ==/!= 0 if a ==/!= b
+ Value *X, *Y;
+ if (ICI->isEquality() && match(Val, m_Sub(m_Value(X), m_Value(Y)))) {
+ // Peek through ptrtoints
+ match(X, m_PtrToIntSameSize(DL, m_Value(X)));
+ match(Y, m_PtrToIntSameSize(DL, m_Value(Y)));
+ if ((X == LHS && Y == RHS) || (X == RHS && Y == LHS)) {
+ Constant *NullVal = Constant::getNullValue(Val->getType());
+ if (EdgePred == ICmpInst::ICMP_EQ)
+ return ValueLatticeElement::get(NullVal);
+ return ValueLatticeElement::getNot(NullVal);
+ }
+ }
+
unsigned BitWidth = Ty->getScalarSizeInBits();
APInt Offset(BitWidth, 0);
if (matchICmpOperand(Offset, LHS, Val, EdgePred))
diff --git a/llvm/test/Transforms/CorrelatedValuePropagation/umax.ll b/llvm/test/Transforms/CorrelatedValuePropagation/umax.ll
new file mode 100644
index 00000000000000..5cd615e948adbe
--- /dev/null
+++ b/llvm/test/Transforms/CorrelatedValuePropagation/umax.ll
@@ -0,0 +1,58 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt < %s -passes=correlated-propagation -S | FileCheck %s
+
+target datalayout = "p:32:32"
+
+define i32 @infer_range_from_dom_equality(i32 %x, i32 %y) {
+; CHECK-LABEL: define range(i32 1, 0) i32 @infer_range_from_dom_equality(
+; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
+; CHECK-NEXT: [[ENTRY:.*:]]
+; CHECK-NEXT: [[COND:%.*]] = icmp eq i32 [[X]], [[Y]]
+; CHECK-NEXT: [[SUB:%.*]] = sub i32 [[X]], [[Y]]
+; CHECK-NEXT: br i1 [[COND]], label %[[IF_THEN:.*]], label %[[IF_ELSE:.*]]
+; CHECK: [[IF_THEN]]:
+; CHECK-NEXT: ret i32 1
+; CHECK: [[IF_ELSE]]:
+; CHECK-NEXT: ret i32 [[SUB]]
+;
+entry:
+ %cond = icmp eq i32 %x, %y
+ %sub = sub i32 %x, %y
+ br i1 %cond, label %if.then, label %if.else
+
+if.then:
+ %max1 = call i32 @llvm.umax.i32(i32 %sub, i32 1)
+ ret i32 %max1
+
+if.else:
+ %max2 = call i32 @llvm.umax.i32(i32 %sub, i32 1)
+ ret i32 %max2
+}
+
+define i32 @infer_range_from_dom_equality_ptrdiff(ptr %x, ptr %y) {
+; CHECK-LABEL: define range(i32 1, 0) i32 @infer_range_from_dom_equality_ptrdiff(
+; CHECK-SAME: ptr [[X:%.*]], ptr [[Y:%.*]]) {
+; CHECK-NEXT: [[COND:%.*]] = icmp eq ptr [[X]], [[Y]]
+; CHECK-NEXT: [[XI:%.*]] = ptrtoint ptr [[X]] to i32
+; CHECK-NEXT: [[YI:%.*]] = ptrtoint ptr [[Y]] to i32
+; CHECK-NEXT: [[SUB:%.*]] = sub i32 [[XI]], [[YI]]
+; CHECK-NEXT: br i1 [[COND]], label %[[IF_THEN:.*]], label %[[IF_ELSE:.*]]
+; CHECK: [[IF_THEN]]:
+; CHECK-NEXT: ret i32 1
+; CHECK: [[IF_ELSE]]:
+; CHECK-NEXT: ret i32 [[SUB]]
+;
+ %cond = icmp eq ptr %x, %y
+ %xi = ptrtoint ptr %x to i32
+ %yi = ptrtoint ptr %y to i32
+ %sub = sub i32 %xi, %yi
+ br i1 %cond, label %if.then, label %if.else
+
+if.then:
+ %max1 = call i32 @llvm.umax.i32(i32 %sub, i32 1)
+ ret i32 %max1
+
+if.else:
+ %max2 = call i32 @llvm.umax.i32(i32 %sub, i32 1)
+ ret i32 %max2
+}
|
|
@llvm/pr-subscribers-llvm-analysis Author: Yingwei Zheng (dtcxzyw) ChangesThis following pattern is common in loop headers: As Addresses regression introduced by #112742. Full diff: https://github.com/llvm/llvm-project/pull/112838.diff 2 Files Affected:
diff --git a/llvm/lib/Analysis/LazyValueInfo.cpp b/llvm/lib/Analysis/LazyValueInfo.cpp
index 10ad4708596cb3..f29777a584772d 100644
--- a/llvm/lib/Analysis/LazyValueInfo.cpp
+++ b/llvm/lib/Analysis/LazyValueInfo.cpp
@@ -1127,6 +1127,20 @@ std::optional<ValueLatticeElement> LazyValueInfoImpl::getValueFromICmpCondition(
if (!Ty->isIntegerTy())
return ValueLatticeElement::getOverdefined();
+ // a - b or ptrtoint(a) - ptrtoint(b) ==/!= 0 if a ==/!= b
+ Value *X, *Y;
+ if (ICI->isEquality() && match(Val, m_Sub(m_Value(X), m_Value(Y)))) {
+ // Peek through ptrtoints
+ match(X, m_PtrToIntSameSize(DL, m_Value(X)));
+ match(Y, m_PtrToIntSameSize(DL, m_Value(Y)));
+ if ((X == LHS && Y == RHS) || (X == RHS && Y == LHS)) {
+ Constant *NullVal = Constant::getNullValue(Val->getType());
+ if (EdgePred == ICmpInst::ICMP_EQ)
+ return ValueLatticeElement::get(NullVal);
+ return ValueLatticeElement::getNot(NullVal);
+ }
+ }
+
unsigned BitWidth = Ty->getScalarSizeInBits();
APInt Offset(BitWidth, 0);
if (matchICmpOperand(Offset, LHS, Val, EdgePred))
diff --git a/llvm/test/Transforms/CorrelatedValuePropagation/umax.ll b/llvm/test/Transforms/CorrelatedValuePropagation/umax.ll
new file mode 100644
index 00000000000000..5cd615e948adbe
--- /dev/null
+++ b/llvm/test/Transforms/CorrelatedValuePropagation/umax.ll
@@ -0,0 +1,58 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt < %s -passes=correlated-propagation -S | FileCheck %s
+
+target datalayout = "p:32:32"
+
+define i32 @infer_range_from_dom_equality(i32 %x, i32 %y) {
+; CHECK-LABEL: define range(i32 1, 0) i32 @infer_range_from_dom_equality(
+; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
+; CHECK-NEXT: [[ENTRY:.*:]]
+; CHECK-NEXT: [[COND:%.*]] = icmp eq i32 [[X]], [[Y]]
+; CHECK-NEXT: [[SUB:%.*]] = sub i32 [[X]], [[Y]]
+; CHECK-NEXT: br i1 [[COND]], label %[[IF_THEN:.*]], label %[[IF_ELSE:.*]]
+; CHECK: [[IF_THEN]]:
+; CHECK-NEXT: ret i32 1
+; CHECK: [[IF_ELSE]]:
+; CHECK-NEXT: ret i32 [[SUB]]
+;
+entry:
+ %cond = icmp eq i32 %x, %y
+ %sub = sub i32 %x, %y
+ br i1 %cond, label %if.then, label %if.else
+
+if.then:
+ %max1 = call i32 @llvm.umax.i32(i32 %sub, i32 1)
+ ret i32 %max1
+
+if.else:
+ %max2 = call i32 @llvm.umax.i32(i32 %sub, i32 1)
+ ret i32 %max2
+}
+
+define i32 @infer_range_from_dom_equality_ptrdiff(ptr %x, ptr %y) {
+; CHECK-LABEL: define range(i32 1, 0) i32 @infer_range_from_dom_equality_ptrdiff(
+; CHECK-SAME: ptr [[X:%.*]], ptr [[Y:%.*]]) {
+; CHECK-NEXT: [[COND:%.*]] = icmp eq ptr [[X]], [[Y]]
+; CHECK-NEXT: [[XI:%.*]] = ptrtoint ptr [[X]] to i32
+; CHECK-NEXT: [[YI:%.*]] = ptrtoint ptr [[Y]] to i32
+; CHECK-NEXT: [[SUB:%.*]] = sub i32 [[XI]], [[YI]]
+; CHECK-NEXT: br i1 [[COND]], label %[[IF_THEN:.*]], label %[[IF_ELSE:.*]]
+; CHECK: [[IF_THEN]]:
+; CHECK-NEXT: ret i32 1
+; CHECK: [[IF_ELSE]]:
+; CHECK-NEXT: ret i32 [[SUB]]
+;
+ %cond = icmp eq ptr %x, %y
+ %xi = ptrtoint ptr %x to i32
+ %yi = ptrtoint ptr %y to i32
+ %sub = sub i32 %xi, %yi
+ br i1 %cond, label %if.then, label %if.else
+
+if.then:
+ %max1 = call i32 @llvm.umax.i32(i32 %sub, i32 1)
+ ret i32 %max1
+
+if.else:
+ %max2 = call i32 @llvm.umax.i32(i32 %sub, i32 1)
+ ret i32 %max2
+}
|
Looks unrelated. |
EricWF
pushed a commit
to efcs/llvm-project
that referenced
this pull request
Oct 22, 2024
This following pattern is common in loop headers: ``` %101 = sub nuw i64 %78, %98 %103 = icmp eq i64 %78, %98 br i1 %103, label %.thread.i.i, label %.preheader.preheader.i.i .preheader.preheader.i.i: %invariant.umin.i.i = call i64 @llvm.umin.i64(i64 %101, i64 9) %umax.i = call i64 @llvm.umax.i64(i64 %invariant.umin.i.i, i64 1) br label %.preheader.i.i .preheader.i.i: ... %116 = add nuw nsw i64 %.011.i.i, 1 %exitcond.not.i = icmp eq i64 %116, %umax.i br i1 %exitcond.not.i, label %.critedge.i.i, label %.preheader.i.i ``` As `%78` is not equal to `%98` in BB `.preheader.preheader.i.i`, we can prove `%101` is non-zero. Then we can simplify the loop exit condition. Addresses regression introduced by llvm#112742.
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This following pattern is common in loop headers:
As
%78is not equal to%98in BB.preheader.preheader.i.i, we can prove%101is non-zero. Then we can simplify the loop exit condition.Addresses regression introduced by #112742.