[llvm] 1da0da9 - [LVI][CVP] Don't compute CR at SelectInst Use if Cond value may not be well-defined
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Fri Apr 21 22:16:26 PDT 2023
Author: luxufan
Date: 2023-04-22T12:54:49+08:00
New Revision: 1da0da903ee818385d8ce470d14f9f9c7cdf6942
URL: https://github.com/llvm/llvm-project/commit/1da0da903ee818385d8ce470d14f9f9c7cdf6942
DIFF: https://github.com/llvm/llvm-project/commit/1da0da903ee818385d8ce470d14f9f9c7cdf6942.diff
LOG: [LVI][CVP] Don't compute CR at SelectInst Use if Cond value may not be well-defined
If the condition value of SelectInst may be a poison or undef value,
infer constant range at SelectInst use is in correct.
See https://alive2.llvm.org/ce/z/MWMTYn
Fixes: https://github.com/llvm/llvm-project/issues/62200
Differential Revision: https://reviews.llvm.org/D148709
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 7bb66f2c96628..3491bcefdcbf7 100644
--- a/llvm/lib/Analysis/LazyValueInfo.cpp
+++ b/llvm/lib/Analysis/LazyValueInfo.cpp
@@ -1667,6 +1667,10 @@ ConstantRange LazyValueInfo::getConstantRangeAtUse(const Use &U,
std::optional<ValueLatticeElement> CondVal;
auto *CurrI = cast<Instruction>(CurrU->getUser());
if (auto *SI = dyn_cast<SelectInst>(CurrI)) {
+ // If the value is undef, a
diff erent value may be chosen in
+ // the select condition and at use.
+ if (!isGuaranteedNotToBeUndefOrPoison(SI->getCondition(), AC))
+ break;
if (CurrU->getOperandNo() == 1)
CondVal = getValueFromCondition(V, SI->getCondition(), true);
else if (CurrU->getOperandNo() == 2)
diff --git a/llvm/test/Transforms/CorrelatedValuePropagation/cond-at-use.ll b/llvm/test/Transforms/CorrelatedValuePropagation/cond-at-use.ll
index 6270ca86bce4a..dbb63203cc945 100644
--- a/llvm/test/Transforms/CorrelatedValuePropagation/cond-at-use.ll
+++ b/llvm/test/Transforms/CorrelatedValuePropagation/cond-at-use.ll
@@ -7,7 +7,7 @@ declare i16 @llvm.uadd.sat.i16(i16, i16)
declare i16 @llvm.umin.i16(i16, i16)
declare i16 @llvm.abs.i16(i16, i1)
-define i16 @sel_true_cond(i16 %x) {
+define i16 @sel_true_cond(i16 noundef %x) {
; CHECK-LABEL: @sel_true_cond(
; CHECK-NEXT: [[SUB1:%.*]] = sub nuw i16 [[X:%.*]], 10
; CHECK-NEXT: [[CMP:%.*]] = icmp uge i16 [[X]], 10
@@ -74,7 +74,7 @@ define i16 @sel_true_cond_extra_use(i16 %x) {
ret i16 %sel
}
-define i16 @sel_true_cond_chain_speculatable(i16 %x) {
+define i16 @sel_true_cond_chain_speculatable(i16 noundef %x) {
; CHECK-LABEL: @sel_true_cond_chain_speculatable(
; CHECK-NEXT: [[SUB1:%.*]] = add nuw i16 [[X:%.*]], 1
; CHECK-NEXT: [[EXTRA:%.*]] = mul i16 [[SUB1]], 3
@@ -123,7 +123,7 @@ define i16 @sel_true_cond_longer_chain(i16 %x) {
ret i16 %sel
}
-define i16 @sel_false_cond(i16 %x) {
+define i16 @sel_false_cond(i16 noundef %x) {
; CHECK-LABEL: @sel_false_cond(
; CHECK-NEXT: [[SUB1:%.*]] = sub nuw i16 [[X:%.*]], 10
; CHECK-NEXT: [[CMP:%.*]] = icmp ult i16 [[X]], 10
@@ -332,7 +332,7 @@ exit:
ret i16 %count
}
-define i16 @urem_elide(i16 %x) {
+define i16 @urem_elide(i16 noundef %x) {
; CHECK-LABEL: @urem_elide(
; CHECK-NEXT: [[CMP:%.*]] = icmp ult i16 [[X:%.*]], 42
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i16 [[X]], i16 24
@@ -344,7 +344,7 @@ define i16 @urem_elide(i16 %x) {
ret i16 %sel
}
-define i16 @urem_expand(i16 %x) {
+define i16 @urem_expand(i16 noundef %x) {
; CHECK-LABEL: @urem_expand(
; CHECK-NEXT: [[X_FROZEN:%.*]] = freeze i16 [[X:%.*]]
; CHECK-NEXT: [[UREM_UREM:%.*]] = sub nuw i16 [[X_FROZEN]], 42
@@ -360,7 +360,7 @@ define i16 @urem_expand(i16 %x) {
ret i16 %sel
}
-define i16 @urem_narrow(i16 %x) {
+define i16 @urem_narrow(i16 noundef %x) {
; CHECK-LABEL: @urem_narrow(
; CHECK-NEXT: [[UREM_LHS_TRUNC:%.*]] = trunc i16 [[X:%.*]] to i8
; CHECK-NEXT: [[UREM1:%.*]] = urem i8 [[UREM_LHS_TRUNC]], 42
@@ -388,7 +388,7 @@ define i16 @urem_insufficient(i16 %x) {
ret i16 %sel
}
-define i16 @srem_elide(i16 %x) {
+define i16 @srem_elide(i16 noundef %x) {
; CHECK-LABEL: @srem_elide(
; CHECK-NEXT: [[CMP1:%.*]] = icmp slt i16 [[X:%.*]], 42
; CHECK-NEXT: [[CMP2:%.*]] = icmp sgt i16 [[X]], -42
@@ -404,7 +404,7 @@ define i16 @srem_elide(i16 %x) {
ret i16 %sel
}
-define i16 @srem_narrow(i16 %x) {
+define i16 @srem_narrow(i16 noundef %x) {
; CHECK-LABEL: @srem_narrow(
; CHECK-NEXT: [[SREM_LHS_TRUNC:%.*]] = trunc i16 [[X:%.*]] to i8
; CHECK-NEXT: [[SREM1:%.*]] = srem i8 [[SREM_LHS_TRUNC]], 42
@@ -423,7 +423,7 @@ define i16 @srem_narrow(i16 %x) {
ret i16 %sel
}
-define i16 @srem_convert(i16 %x) {
+define i16 @srem_convert(i16 noundef %x) {
; CHECK-LABEL: @srem_convert(
; CHECK-NEXT: [[X_NONNEG:%.*]] = sub i16 0, [[X:%.*]]
; CHECK-NEXT: [[SREM1:%.*]] = urem i16 [[X_NONNEG]], 42
@@ -438,7 +438,7 @@ define i16 @srem_convert(i16 %x) {
ret i16 %sel
}
-define i16 @sdiv_convert(i16 %x) {
+define i16 @sdiv_convert(i16 noundef %x) {
; CHECK-LABEL: @sdiv_convert(
; CHECK-NEXT: [[X_NONNEG:%.*]] = sub i16 0, [[X:%.*]]
; CHECK-NEXT: [[SREM1:%.*]] = udiv i16 [[X_NONNEG]], 42
@@ -505,7 +505,7 @@ define i16 @umin_elide(i16 %x) {
ret i16 %sel
}
-define i16 @ashr_convert(i16 %x, i16 %y) {
+define i16 @ashr_convert(i16 noundef %x, i16 %y) {
; CHECK-LABEL: @ashr_convert(
; CHECK-NEXT: [[ASHR:%.*]] = lshr i16 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[CMP:%.*]] = icmp sge i16 [[X]], 0
@@ -518,7 +518,7 @@ define i16 @ashr_convert(i16 %x, i16 %y) {
ret i16 %sel
}
-define i32 @sext_convert(i16 %x) {
+define i32 @sext_convert(i16 noundef %x) {
; CHECK-LABEL: @sext_convert(
; CHECK-NEXT: [[EXT:%.*]] = zext i16 [[X:%.*]] to i32
; CHECK-NEXT: [[CMP:%.*]] = icmp sge i16 [[X]], 0
@@ -544,7 +544,7 @@ define i16 @infer_flags(i16 %x) {
ret i16 %sel
}
-define i16 @and_elide(i16 %x) {
+define i16 @and_elide(i16 noundef %x) {
; CHECK-LABEL: @and_elide(
; CHECK-NEXT: [[CMP:%.*]] = icmp ult i16 [[X:%.*]], 8
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i16 [[X]], i16 24
@@ -555,3 +555,16 @@ define i16 @and_elide(i16 %x) {
%sel = select i1 %cmp, i16 %and, i16 24
ret i16 %sel
}
+
+define i16 @cond_value_may_not_well_defined(i16 %x) {
+; CHECK-LABEL: @cond_value_may_not_well_defined(
+; CHECK-NEXT: [[AND:%.*]] = and i16 [[X:%.*]], 7
+; CHECK-NEXT: [[CMP:%.*]] = icmp ult i16 [[X]], 8
+; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i16 [[AND]], i16 24
+; CHECK-NEXT: ret i16 [[SEL]]
+;
+ %and = and i16 %x, 7
+ %cmp = icmp ult i16 %x, 8
+ %sel = select i1 %cmp, i16 %and, i16 24
+ ret i16 %sel
+}
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