replica
/
hanchenye-llvm-project
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

[ValueTracking] Support icmps fed by 'and' and 'or'. 

This patch adds support for handling some forms of ands and ors in
ValueTracking's isImpliedCondition API.

PR33611
https://reviews.llvm.org/D34901

llvm-svn: 307304
This commit is contained in:
Chad Rosier 2017-07-06 20:00:25 +00:00
parent 6a5fbe52fa
commit a72a9ff557
4 changed files with 258 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
llvm/include/llvm/Analysis/ValueTracking.h
View File

@ -523,8 +523,7 @@ template <typename T> class ArrayRef;
/// (A)
Optional<bool> isImpliedCondition(const Value *LHS, const Value *RHS,
const DataLayout &DL,
bool InvertAPred = false,
unsigned Depth = 0,
bool LHSIsFalse = false, unsigned Depth = 0,
AssumptionCache *AC = nullptr,
const Instruction *CxtI = nullptr,
const DominatorTree *DT = nullptr);

41
llvm/lib/Analysis/ValueTracking.cpp
View File

@ -4393,7 +4393,7 @@ isImpliedCondMatchingImmOperands(CmpInst::Predicate APred, const Value *ALHS,
}
Optional<bool> llvm::isImpliedCondition(const Value *LHS, const Value *RHS,
const DataLayout &DL, bool InvertAPred,
const DataLayout &DL, bool LHSIsFalse,
unsigned Depth, AssumptionCache *AC,
const Instruction *CxtI,
const DominatorTree *DT) {
@ -4405,7 +4405,7 @@ Optional<bool> llvm::isImpliedCondition(const Value *LHS, const Value *RHS,
assert(OpTy->getScalarType()->isIntegerTy(1));
// LHS ==> RHS by definition
if (!InvertAPred && LHS == RHS)
if (!LHSIsFalse && LHS == RHS)
return true;
if (OpTy->isVectorTy())
@ -4413,15 +4413,40 @@ Optional<bool> llvm::isImpliedCondition(const Value *LHS, const Value *RHS,
return None;
assert(OpTy->isIntegerTy(1) && "implied by above");
ICmpInst::Predicate APred, BPred;
Value *ALHS, *ARHS;
Value *BLHS, *BRHS;
if (!match(LHS, m_ICmp(APred, m_Value(ALHS), m_Value(ARHS))) ||
!match(RHS, m_ICmp(BPred, m_Value(BLHS), m_Value(BRHS))))
ICmpInst::Predicate BPred;
// We expect the RHS to be an icmp.
if (!match(RHS, m_ICmp(BPred, m_Value(BLHS), m_Value(BRHS))))
return None;
if (InvertAPred)
Value *ALHS, *ARHS;
ICmpInst::Predicate APred;
// The LHS can be an 'or', 'and', or 'icmp'.
if (!match(LHS, m_ICmp(APred, m_Value(ALHS), m_Value(ARHS)))) {
// The remaining tests are all recursive, so bail out if we hit the limit.
if (Depth == MaxDepth)
return None;
// If the result of an 'or' is false, then we know both legs of the 'or' are
// false. Similarly, if the result of an 'and' is true, then we know both
// legs of the 'and' are true.
if ((LHSIsFalse && match(LHS, m_Or(m_Value(ALHS), m_Value(ARHS)))) ||
(!LHSIsFalse && match(LHS, m_And(m_Value(ALHS), m_Value(ARHS))))) {
if (Optional<bool> Implication = isImpliedCondition(
ALHS, RHS, DL, LHSIsFalse, Depth + 1, AC, CxtI, DT))
return Implication;
if (Optional<bool> Implication = isImpliedCondition(
ARHS, RHS, DL, LHSIsFalse, Depth + 1, AC, CxtI, DT))
return Implication;
return None;
}
return None;
}
// All of the below logic assumes both LHS and RHS are icmps.
assert(isa<ICmpInst>(LHS) && isa<ICmpInst>(RHS) && "Expected icmps.");
// The rest of the logic assumes the LHS condition is true. If that's not the
// case, invert the predicate to make it so.
if (LHSIsFalse)
APred = CmpInst::getInversePredicate(APred);
// Can we infer anything when the two compares have matching operands?

41
llvm/test/Transforms/InstCombine/select-implied.ll
View File

@ -121,3 +121,44 @@ end:
declare void @foo(i32)
declare i32 @bar(i32)
; CHECK-LABEL: @test_and
; CHECK: tpath:
; CHECK-NOT: select
; CHECK: ret i32 313
define i32 @test_and(i32 %a, i32 %b) {
entry:
%cmp1 = icmp ne i32 %a, 0
%cmp2 = icmp ne i32 %b, 0
%and = and i1 %cmp1, %cmp2
br i1 %and, label %tpath, label %end
tpath:
%cmp3 = icmp eq i32 %a, 0 ;; <-- implied false
%c = select i1 %cmp3, i32 0, i32 313
ret i32 %c
end:
ret i32 0
}
; cmp1 and cmp2 are false on the 'fpath' path and thus cmp3 is true.
; CHECK-LABEL: @test_or1
; CHECK: fpath:
; CHECK-NOT: select
; CHECK: ret i32 37
define i32 @test_or1(i32 %a, i32 %b) {
entry:
%cmp1 = icmp eq i32 %a, 0
%cmp2 = icmp eq i32 %b, 0
%or = or i1 %cmp1, %cmp2
br i1 %or, label %end, label %fpath
fpath:
%cmp3 = icmp ne i32 %a, 0 ;; <-- implied true
%c = select i1 %cmp3, i32 37, i32 0
ret i32 %c
end:
ret i32 0
}

183
llvm/test/Transforms/SimplifyCFG/implied-and-or.ll Normal file
View File

@ -0,0 +1,183 @@
; RUN: opt %s -S -simplifycfg | FileCheck %s
declare void @foo()
declare void @bar()
; CHECK-LABEL: @test_and1
; CHECK: taken:
; CHECK-NOT: cmp3
; CHECK: call void @bar()
; CHECK-NEXT: call void @foo()
; CHECK: ret
define void @test_and1(i32 %a, i32 %b) {
entry:
%cmp1 = icmp eq i32 %a, 0
%cmp2 = icmp eq i32 %b, 0
%and = and i1 %cmp1, %cmp2
br i1 %and, label %taken, label %end
taken:
call void @bar()
%cmp3 = icmp eq i32 %a, 0 ;; <-- implied true
br i1 %cmp3, label %if.then, label %end
if.then:
call void @foo()
br label %end
end:
ret void
}
; We can't infer anything if the result of the 'and' is false
; CHECK-LABEL: @test_and2
; CHECK: taken:
; CHECK: call void @bar()
; CHECK: %cmp3
; CHECK: br i1 %cmp3
; CHECK: if.then:
; CHECK: call void @foo()
; CHECK: ret
define void @test_and2(i32 %a, i32 %b) {
entry:
%cmp1 = icmp eq i32 %a, 0
%cmp2 = icmp eq i32 %b, 0
%and = and i1 %cmp1, %cmp2
br i1 %and, label %end, label %taken
taken:
call void @bar()
%cmp3 = icmp eq i32 %a, 0
br i1 %cmp3, label %if.then, label %end
if.then:
call void @foo()
br label %end
end:
ret void
}
; CHECK-LABEL: @test_or1
; CHECK: taken:
; CHECK-NOT: cmp3
; CHECK: call void @bar()
; CHECK-NEXT: call void @foo()
; CHECK: ret
define void @test_or1(i32 %a, i32 %b) {
entry:
%cmp1 = icmp eq i32 %a, 0
%cmp2 = icmp eq i32 %b, 0
%or = or i1 %cmp1, %cmp2
br i1 %or, label %end, label %taken
taken:
call void @bar()
%cmp3 = icmp ne i32 %a, 0 ;; <-- implied true
br i1 %cmp3, label %if.then, label %end
if.then:
call void @foo()
br label %end
end:
ret void
}
; We can't infer anything if the result of the 'or' is true
; CHECK-LABEL: @test_or2
; CHECK: call void @bar()
; CHECK: %cmp3
; CHECK: br i1 %cmp3
; CHECK: if.then:
; CHECK: call void @foo()
; CHECK: ret
define void @test_or2(i32 %a, i32 %b) {
entry:
%cmp1 = icmp eq i32 %a, 0
%cmp2 = icmp eq i32 %b, 0
%or = or i1 %cmp1, %cmp2
br i1 %or, label %taken, label %end
taken:
call void @bar()
%cmp3 = icmp eq i32 %a, 0
br i1 %cmp3, label %if.then, label %end
if.then:
call void @foo()
br label %end
end:
ret void
}
; We can recurse a tree of 'and' or 'or's.
; CHECK-LABEL: @test_and_recurse1
; CHECK: taken:
; CHECK-NEXT: call void @bar()
; CHECK-NEXT: call void @foo()
; CHECK-NEXT: br label %end
; CHECK: ret
define void @test_and_recurse1(i32 %a, i32 %b, i32 %c) {
entry:
%cmpa = icmp eq i32 %a, 0
%cmpb = icmp eq i32 %b, 0
%cmpc = icmp eq i32 %c, 0
%and1 = and i1 %cmpa, %cmpb
%and2 = and i1 %and1, %cmpc
br i1 %and2, label %taken, label %end
taken:
call void @bar()
%cmp3 = icmp eq i32 %a, 0
br i1 %cmp3, label %if.then, label %end
if.then:
call void @foo()
br label %end
end:
ret void
}
; Check to make sure we don't recurse too deep.
; CHECK-LABEL: @test_and_recurse2
; CHECK: taken:
; CHECK-NEXT: call void @bar()
; CHECK-NEXT: %cmp3 = icmp eq i32 %a, 0
; CHECK-NEXT: br i1 %cmp3, label %if.then, label %end
; CHECK: ret
define void @test_and_recurse2(i32 %a, i32 %b, i32 %c, i32 %d, i32 %e, i32 %f,
i32 %g, i32 %h) {
entry:
%cmpa = icmp eq i32 %a, 0
%cmpb = icmp eq i32 %b, 0
%cmpc = icmp eq i32 %c, 0
%cmpd = icmp eq i32 %d, 0
%cmpe = icmp eq i32 %e, 0
%cmpf = icmp eq i32 %f, 0
%cmpg = icmp eq i32 %g, 0
%cmph = icmp eq i32 %h, 0
%and1 = and i1 %cmpa, %cmpb
%and2 = and i1 %and1, %cmpc
%and3 = and i1 %and2, %cmpd
%and4 = and i1 %and3, %cmpe
%and5 = and i1 %and4, %cmpf
%and6 = and i1 %and5, %cmpg
%and7 = and i1 %and6, %cmph
br i1 %and7, label %taken, label %end
taken:
call void @bar()
%cmp3 = icmp eq i32 %a, 0 ; <-- can be implied true
br i1 %cmp3, label %if.then, label %end
if.then:
call void @foo()
br label %end
end:
ret void
}