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[CVP] Allow two transforms in one invocation 

For a call site which had both constant deopt operands and nonnull arguments, we were missing the opportunity to recognize the later by bailing early.

This is somewhat of a speculative fix.  Months ago, I'd had a private report of performance and compile time regressions from the deopt operand folding.  I never received a test case.  However, the only possibility I see was that after that change CVP missed the nonnull fold, and we end up with a pass ordering/missed simplification issue.  So, since it's a real issue, fix it and hope.
This commit is contained in:
Philip Reames 2020-09-28 15:08:25 -07:00
parent bd08a87cfe
commit e46d74b589
2 changed files with 29 additions and 7 deletions
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14
llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
View File

@ -524,8 +524,6 @@ static void processSaturatingInst(SaturatingInst *SI, LazyValueInfo *LVI) {
/// Infer nonnull attributes for the arguments at the specified callsite.
static bool processCallSite(CallBase &CB, LazyValueInfo *LVI) {
SmallVector<unsigned, 4> ArgNos;
unsigned ArgNo = 0;
if (auto *WO = dyn_cast<WithOverflowInst>(&CB)) {
if (WO->getLHS()->getType()->isIntegerTy() && willNotOverflow(WO, LVI)) {
@ -541,6 +539,8 @@ static bool processCallSite(CallBase &CB, LazyValueInfo *LVI) {
}
}
bool Changed = false;
// Deopt bundle operands are intended to capture state with minimal
// perturbance of the code otherwise. If we can find a constant value for
// any such operand and remove a use of the original value, that's
@ -549,7 +549,6 @@ static bool processCallSite(CallBase &CB, LazyValueInfo *LVI) {
// idiomatically, appear along rare conditional paths, it's reasonable likely
// we may have a conditional fact with which LVI can fold.
if (auto DeoptBundle = CB.getOperandBundle(LLVMContext::OB_deopt)) {
bool Progress = false;
for (const Use &ConstU : DeoptBundle->Inputs) {
Use &U = const_cast<Use&>(ConstU);
Value *V = U.get();
@ -559,12 +558,13 @@ static bool processCallSite(CallBase &CB, LazyValueInfo *LVI) {
Constant *C = LVI->getConstant(V, &CB);
if (!C) continue;
U.set(C);
Progress = true;
Changed = true;
}
if (Progress)
return true;
}
SmallVector<unsigned, 4> ArgNos;
unsigned ArgNo = 0;
for (Value *V : CB.args()) {
PointerType *Type = dyn_cast<PointerType>(V->getType());
// Try to mark pointer typed parameters as non-null. We skip the
@ -582,7 +582,7 @@ static bool processCallSite(CallBase &CB, LazyValueInfo *LVI) {
assert(ArgNo == CB.arg_size() && "sanity check");
if (ArgNos.empty())
return false;
return Changed;
AttributeList AS = CB.getAttributes();
LLVMContext &Ctx = CB.getContext();

22
llvm/test/Transforms/CorrelatedValuePropagation/deopt.ll
View File

@ -2,6 +2,8 @@
; RUN: opt -correlated-propagation -S < %s | FileCheck %s
declare void @use()
declare void @use_ptr(i8*)
; test requires a mix of context sensative refinement, and analysis
; of the originating IR pattern. Neither part is enough in isolation.
define void @test1(i1 %c, i1 %c2) {
@ -140,3 +142,23 @@ taken:
untaken:
ret void
}
define void @test5(i64 %a, i8* nonnull %p) {
; CHECK-LABEL: @test5(
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i64 [[A:%.*]], 0
; CHECK-NEXT: br i1 [[CMP]], label [[TAKEN:%.*]], label [[UNTAKEN:%.*]]
; CHECK: taken:
; CHECK-NEXT: call void @use_ptr(i8* nonnull [[P:%.*]]) [ "deopt"(i64 0) ]
; CHECK-NEXT: ret void
; CHECK: untaken:
; CHECK-NEXT: ret void
;
%cmp = icmp eq i64 %a, 0
br i1 %cmp, label %taken, label %untaken
taken:
call void @use_ptr(i8* %p) ["deopt" (i64 %a)]
ret void
untaken:
ret void
}