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[LVI] Handle any predicate in comparisons like icmp <pred> (add Val, Offset), ...

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Currently LVI can only gather value constraints from comparisons like:

* icmp <pred> Val, ...
* icmp ult (add Val, Offset), ...

In fact we can handle any predicate in latter comparisons.

Reviewed By: sanjoy

Differential Revision: https://reviews.llvm.org/D23357

llvm-svn: 278493
This commit is contained in:
Artur Pilipenko 2016-08-12 10:05:11 +00:00
parent 21c5b60822
commit 62de453cec
2 changed files with 132 additions and 2 deletions
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4
lib/Analysis/LazyValueInfo.cpp
View File

@ -1191,7 +1191,7 @@ static LVILatticeVal getValueFromICmpCondition(Value *Val, ICmpInst *ICI,
// range of Val guaranteed by the condition. Recognize comparisons in the from
// of:
// icmp <pred> Val, ...
// icmp ult (add Val, Offset), ...
// icmp <pred> (add Val, Offset), ...
// The latter is the range checking idiom that InstCombine produces. Subtract
// the offset from the allowed range for RHS in this case.
@ -1202,7 +1202,7 @@ static LVILatticeVal getValueFromICmpCondition(Value *Val, ICmpInst *ICI,
}
ConstantInt *Offset = nullptr;
if (Predicate == ICmpInst::ICMP_ULT)
if (LHS != Val)
match(LHS, m_Add(m_Specific(Val), m_ConstantInt(Offset)));
if (LHS == Val || Offset) {

130
test/Transforms/CorrelatedValuePropagation/range.ll
View File

@ -315,3 +315,133 @@ else:
end:
ret i32 2
}
define i1 @test14_slt(i32 %a) {
; CHECK-LABEL: @test14_slt(
; CHECK: then:
; CHECK-NEXT: %result = or i1 false, false
%a.off = add i32 %a, -8
%cmp = icmp slt i32 %a.off, 8
br i1 %cmp, label %then, label %else
then:
%dead.1 = icmp eq i32 %a, -2147483641
%dead.2 = icmp eq i32 %a, 16
%result = or i1 %dead.1, %dead.2
ret i1 %result
else:
ret i1 false
}
define i1 @test14_sle(i32 %a) {
; CHECK-LABEL: @test14_sle(
; CHECK: then:
; CHECK-NEXT: %alive = icmp eq i32 %a, 16
; CHECK-NEXT: %result = or i1 false, %alive
%a.off = add i32 %a, -8
%cmp = icmp sle i32 %a.off, 8
br i1 %cmp, label %then, label %else
then:
%dead = icmp eq i32 %a, -2147483641
%alive = icmp eq i32 %a, 16
%result = or i1 %dead, %alive
ret i1 %result
else:
ret i1 false
}
define i1 @test14_sgt(i32 %a) {
; CHECK-LABEL: @test14_sgt(
; CHECK: then:
; CHECK-NEXT: %result = or i1 false, false
%a.off = add i32 %a, -8
%cmp = icmp sgt i32 %a.off, 8
br i1 %cmp, label %then, label %else
then:
%dead.1 = icmp eq i32 %a, -2147483640
%dead.2 = icmp eq i32 %a, 16
%result = or i1 %dead.1, %dead.2
ret i1 %result
else:
ret i1 false
}
define i1 @test14_sge(i32 %a) {
; CHECK-LABEL: @test14_sge(
; CHECK: then:
; CHECK-NEXT: %alive = icmp eq i32 %a, 16
; CHECK-NEXT: %result = or i1 false, %alive
%a.off = add i32 %a, -8
%cmp = icmp sge i32 %a.off, 8
br i1 %cmp, label %then, label %else
then:
%dead = icmp eq i32 %a, -2147483640
%alive = icmp eq i32 %a, 16
%result = or i1 %dead, %alive
ret i1 %result
else:
ret i1 false
}
define i1 @test14_ule(i32 %a) {
; CHECK-LABEL: @test14_ule(
; CHECK: then:
; CHECK-NEXT: %alive = icmp eq i32 %a, 16
; CHECK-NEXT: %result = or i1 false, %alive
%a.off = add i32 %a, -8
%cmp = icmp ule i32 %a.off, 8
br i1 %cmp, label %then, label %else
then:
%dead = icmp eq i32 %a, 7
%alive = icmp eq i32 %a, 16
%result = or i1 %dead, %alive
ret i1 %result
else:
ret i1 false
}
define i1 @test14_ugt(i32 %a) {
; CHECK-LABEL: @test14_ugt(
; CHECK: then:
; CHECK-NEXT: %result = or i1 false, false
%a.off = add i32 %a, -8
%cmp = icmp ugt i32 %a.off, 8
br i1 %cmp, label %then, label %else
then:
%dead.1 = icmp eq i32 %a, 8
%dead.2 = icmp eq i32 %a, 16
%result = or i1 %dead.1, %dead.2
ret i1 %result
else:
ret i1 false
}
define i1 @test14_uge(i32 %a) {
; CHECK-LABEL: @test14_uge(
; CHECK: then:
; CHECK-NEXT: %alive = icmp eq i32 %a, 16
; CHECK-NEXT: %result = or i1 false, %alive
%a.off = add i32 %a, -8
%cmp = icmp uge i32 %a.off, 8
br i1 %cmp, label %then, label %else
then:
%dead = icmp eq i32 %a, 8
%alive = icmp eq i32 %a, 16
%result = or i1 %dead, %alive
ret i1 %result
else:
ret i1 false
}