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[InstCombine] Allow InstCombine to merge adjacent guards 

Summary:
If there are two adjacent guards with different conditions, we can
remove one of them and include its condition into the condition of
another one. This patch allows InstCombine to merge them by the
following pattern:

    guard(a); guard(b) -> guard(a & b).

Reviewers: reames, apilipenko, igor-laevsky, anna, sanjoy

Reviewed By: sanjoy

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D29378

llvm-svn: 293778
This commit is contained in:
Sanjoy Das 2017-02-01 16:34:55 +00:00
parent ca931efc21
commit e0e5795f6b
2 changed files with 24 additions and 14 deletions
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20
llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
View File

@ -3255,16 +3255,24 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
}
case Intrinsic::experimental_guard: {
Value *IIOperand = II->getArgOperand(0);
// Is this guard followed by another guard?
Instruction *NextInst = II->getNextNode();
Value *NextCond = nullptr;
if (match(NextInst,
m_Intrinsic<Intrinsic::experimental_guard>(m_Value(NextCond)))) {
Value *CurrCond = II->getArgOperand(0);
// Remove a guard if it is immediately followed by an identical guard.
if (match(II->getNextNode(),
m_Intrinsic<Intrinsic::experimental_guard>(m_Specific(IIOperand))))
return eraseInstFromFunction(*II);
// Remove a guard that it is immediately preceeded by an identical guard.
if (CurrCond == NextCond)
return eraseInstFromFunction(*NextInst);
// Otherwise canonicalize guard(a); guard(b) -> guard(a & b).
II->setArgOperand(0, Builder->CreateAnd(CurrCond, NextCond));
return eraseInstFromFunction(*NextInst);
}
break;
}
}
return visitCallSite(II);
}

18
llvm/test/Transforms/InstCombine/call-guard.ll
View File

@ -2,8 +2,8 @@
declare void @llvm.experimental.guard(i1, ...)
define void @test_guard_adjacent(i1 %A) {
; CHECK-LABEL: @test_guard_adjacent(
define void @test_guard_adjacent_same_cond(i1 %A) {
; CHECK-LABEL: @test_guard_adjacent_same_cond(
; CHECK-NEXT: call void (i1, ...) @llvm.experimental.guard(i1 %A) [ "deopt"() ]
; CHECK-NEXT: ret void
call void(i1, ...) @llvm.experimental.guard( i1 %A )[ "deopt"() ]
@ -19,12 +19,14 @@ define void @test_guard_adjacent(i1 %A) {
ret void
}
define void @test_guard_adjacent_neg(i1 %A, i1 %B) {
; CHECK-LABEL: @test_guard_adjacent_neg(
; CHECK-NEXT: call void (i1, ...) @llvm.experimental.guard(i1 %A) [ "deopt"() ]
; CHECK-NEXT: call void (i1, ...) @llvm.experimental.guard(i1 %B) [ "deopt"() ]
define void @test_guard_adjacent_diff_cond(i1 %A, i1 %B, i1 %C) {
; CHECK-LABEL: @test_guard_adjacent_diff_cond(
; CHECK-NEXT: %1 = and i1 %A, %B
; CHECK-NEXT: %2 = and i1 %1, %C
; CHECK-NEXT: call void (i1, ...) @llvm.experimental.guard(i1 %2, i32 123) [ "deopt"() ]
; CHECK-NEXT: ret void
call void(i1, ...) @llvm.experimental.guard( i1 %A )[ "deopt"() ]
call void(i1, ...) @llvm.experimental.guard( i1 %B )[ "deopt"() ]
call void(i1, ...) @llvm.experimental.guard( i1 %A, i32 123 )[ "deopt"() ]
call void(i1, ...) @llvm.experimental.guard( i1 %B, i32 456 )[ "deopt"() ]
call void(i1, ...) @llvm.experimental.guard( i1 %C, i32 789 )[ "deopt"() ]
ret void
}