[ARM] Allow truncs as sources in ARM CGP
We previously only allowed truncs as sinks, but now allow them as
sources too. We do this by checking that the result type is the
narrow type that we're trying to optimise for.
Differential Revision: https://reviews.llvm.org/D51978
llvm-svn: 342141
diff --git a/llvm/lib/Target/ARM/ARMCodeGenPrepare.cpp b/llvm/lib/Target/ARM/ARMCodeGenPrepare.cpp
index 28bb482..e06f05a 100644
--- a/llvm/lib/Target/ARM/ARMCodeGenPrepare.cpp
+++ b/llvm/lib/Target/ARM/ARMCodeGenPrepare.cpp
@@ -175,7 +175,6 @@
/// dealing with icmps but allow any other integer that is <= 16 bits. Void
/// types are accepted so we can handle switches.
static bool isSupportedType(Value *V) {
- LLVM_DEBUG(dbgs() << "ARM CGP: isSupportedType: " << *V << "\n");
Type *Ty = V->getType();
// Allow voids and pointers, these won't be promoted.
@@ -186,10 +185,8 @@
Ty = cast<PointerType>(Ld->getPointerOperandType())->getElementType();
const IntegerType *IntTy = dyn_cast<IntegerType>(Ty);
- if (!IntTy) {
- LLVM_DEBUG(dbgs() << "ARM CGP: No, not an integer.\n");
+ if (!IntTy)
return false;
- }
return IntTy->getBitWidth() == ARMCodeGenPrepare::TypeSize;
}
@@ -204,7 +201,7 @@
static bool isSource(Value *V) {
if (!isa<IntegerType>(V->getType()))
return false;
- // TODO Allow truncs and zext to be sources.
+ // TODO Allow zext to be sources.
if (isa<Argument>(V))
return true;
else if (isa<LoadInst>(V))
@@ -213,6 +210,8 @@
return true;
else if (auto *Call = dyn_cast<CallInst>(V))
return Call->hasRetAttr(Attribute::AttrKind::ZExt);
+ else if (auto *Trunc = dyn_cast<TruncInst>(V))
+ return isSupportedType(Trunc);
return false;
}
@@ -275,10 +274,8 @@
}
static bool shouldPromote(Value *V) {
- if (!isa<IntegerType>(V->getType()) || isSink(V)) {
- LLVM_DEBUG(dbgs() << "ARM CGP: Don't need to promote: " << *V << "\n");
+ if (!isa<IntegerType>(V->getType()) || isSink(V))
return false;
- }
if (isSource(V))
return true;
@@ -358,7 +355,7 @@
Users.push_back(User);
}
- for (auto &U : Users)
+ for (auto *U : Users)
U->replaceUsesOfWith(From, To);
};
@@ -502,6 +499,15 @@
}
}
LLVM_DEBUG(dbgs() << "ARM CGP: Mutation complete:\n");
+ LLVM_DEBUG(dbgs();
+ for (auto *V : Sources)
+ V->dump();
+ for (auto *I : NewInsts)
+ I->dump();
+ for (auto *V : Visited) {
+ if (!Sources.count(V))
+ V->dump();
+ });
}
/// We accept most instructions, as well as Arguments and ConstantInsts. We
@@ -509,8 +515,6 @@
/// return value is zeroext. We don't allow opcodes that can introduce sign
/// bits.
bool ARMCodeGenPrepare::isSupportedValue(Value *V) {
- LLVM_DEBUG(dbgs() << "ARM CGP: Is " << *V << " supported?\n");
-
if (isa<ICmpInst>(V))
return true;
@@ -530,7 +534,11 @@
isa<LoadInst>(V))
return isSupportedType(V);
- if (isa<CastInst>(V) && !isa<SExtInst>(V))
+ // Truncs can be either sources or sinks.
+ if (auto *Trunc = dyn_cast<TruncInst>(V))
+ return isSupportedType(Trunc) || isSupportedType(Trunc->getOperand(0));
+
+ if (isa<CastInst>(V) && !isa<SExtInst>(V))
return isSupportedType(cast<CastInst>(V)->getOperand(0));
// Special cases for calls as we need to check for zeroext
@@ -540,10 +548,9 @@
return isSupportedType(Call) &&
Call->hasRetAttr(Attribute::AttrKind::ZExt);
- if (!isa<BinaryOperator>(V)) {
- LLVM_DEBUG(dbgs() << "ARM CGP: No, not a binary operator.\n");
+ if (!isa<BinaryOperator>(V))
return false;
- }
+
if (!isSupportedType(V))
return false;
@@ -645,10 +652,8 @@
// the tree has already been explored.
// TODO: This could limit the transform, ie if we try to promote something
// from an i8 and fail first, before trying an i16.
- if (AllVisited.count(V)) {
- LLVM_DEBUG(dbgs() << "ARM CGP: Already visited this: " << *V << "\n");
+ if (AllVisited.count(V))
return false;
- }
CurrentVisited.insert(V);
AllVisited.insert(V);
@@ -728,7 +733,6 @@
if (CI.isSigned() || !isa<IntegerType>(CI.getOperand(0)->getType()))
continue;
- LLVM_DEBUG(dbgs() << "ARM CGP: Searching from: " << CI << "\n");
for (auto &Op : CI.operands()) {
if (auto *I = dyn_cast<Instruction>(Op))
MadeChange |= TryToPromote(I);