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indvars -disable-iv-rewrite: handle an edge case involving identity phis.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@134124 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Andrew Trick 2011-06-30 01:27:23 +00:00
parent 5244c4cc2f
commit 60ac719c85
2 changed files with 40 additions and 10 deletions
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11
lib/Transforms/Scalar/IndVarSimplify.cpp
View File

@ -1015,9 +1015,9 @@ bool IndVarSimplify::EliminateIVUser(Instruction *UseInst,
(SE->getSCEV(UseInst) != SE->getSCEV(IVOperand)))
return false;
UseInst->replaceAllUsesWith(IVOperand);
DEBUG(dbgs() << "INDVARS: Eliminated identity: " << *UseInst << '\n');
UseInst->replaceAllUsesWith(IVOperand);
++NumElimIdentity;
Changed = true;
DeadInsts.push_back(UseInst);
@ -1037,7 +1037,9 @@ static void pushIVUsers(
// Avoid infinite or exponential worklist processing.
// Also ensure unique worklist users.
if (Simplified.insert(User))
// If Def is a LoopPhi, it may not be in the Simplified set, so check for
// self edges first.
if (User != Def && Simplified.insert(User))
SimpleIVUsers.push_back(std::make_pair(User, Def));
}
}
@ -1111,6 +1113,9 @@ void IndVarSimplify::SimplifyIVUsersNoRewrite(Loop *L, SCEVExpander &Rewriter) {
// Use-def pairs if IVUsers waiting to be processed for CurrIV.
SmallVector<std::pair<Instruction*, Instruction*>, 8> SimpleIVUsers;
// Push users of the current LoopPhi. In rare cases, pushIVUsers may be
// called multiple times for the same LoopPhi. This is the proper thing to
// do for loop header phis that use each other.
pushIVUsers(CurrIV, Simplified, SimpleIVUsers);
while (!SimpleIVUsers.empty()) {

39
test/Transforms/IndVarSimplify/no-iv-rewrite.ll
View File

@ -23,7 +23,7 @@ ph:
; sext should be eliminated while preserving gep inboundsness.
; CHECK-NOT: sext
; CHECK: getelementptr inbounds
; CHECK: exit
; CHECK: exit:
loop:
%i.02 = phi i32 [ 0, %ph ], [ %iinc, %loop ]
%s.01 = phi i32 [ 0, %ph ], [ %sinc, %loop ]
@ -64,7 +64,7 @@ ph:
; CHECK: getelementptr inbounds
; %vall sext should obviously not be eliminated
; CHECK: sext
; CHECK: exit
; CHECK: exit:
loop:
%i.02 = phi i32 [ 0, %ph ], [ %iinc, %loop ]
%s.01 = phi i64 [ 0, %ph ], [ %sinc, %loop ]
@ -108,7 +108,7 @@ ph:
; Preserve gep inboundsness, and don't factor it.
; CHECK: getelementptr inbounds i32* %ptriv, i32 1
; CHECK-NOT: add
; CHECK: exit
; CHECK: exit:
loop:
%ptriv = phi i32* [ %first, %ph ], [ %ptrpost, %loop ]
%ofs = sext i32 %idx to i64
@ -139,7 +139,7 @@ entry:
; CHECK: phi i32
; CHECK: bitcast
; CHECK: getelementptr
; CHECK: exit
; CHECK: exit:
loop:
%iv = phi i32 [%start, %entry], [%next, %loop]
%p = phi %struct* [%base, %entry], [%pinc, %loop]
@ -157,12 +157,13 @@ exit:
}
define void @maxvisitor(i32 %limit, i32* %base) nounwind {
entry: br label %loop
entry:
br label %loop
; CHECK: loop:
; CHECK: phi i64
; CHECK: trunc
; CHECK: exit
; CHECK: exit:
loop:
%idx = phi i32 [ 0, %entry ], [ %idx.next, %loop.inc ]
%max = phi i32 [ 0, %entry ], [ %max.next, %loop.inc ]
@ -186,4 +187,28 @@ loop.inc:
exit:
ret void
}
}
; CHECK: loop:
; CHECK: phi i32
; CHECK-NOT: phi
; CHECK: exit:
define void @identityphi(i32 %limit) nounwind {
entry:
br label %loop
loop:
%iv = phi i32 [ 0, %entry], [ %iv.next, %control ]
br i1 undef, label %if.then, label %control
if.then:
br label %control
control:
%iv.next = phi i32 [ %iv, %loop ], [ undef, %if.then ]
%cmp = icmp slt i32 %iv.next, %limit
br i1 %cmp, label %loop, label %exit
exit:
ret void
}