This is an archive of the discontinued LLVM Phabricator instance.

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	/// types and vectors of integers.			/// types and vectors of integers.
	bool isKnownToBeAPowerOfTwo(const Value *V, bool OrZero, unsigned Depth,			bool isKnownToBeAPowerOfTwo(const Value *V, bool OrZero, unsigned Depth,
	const SimplifyQuery &Q) {			const SimplifyQuery &Q) {
	assert(Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth");			assert(Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth");

	if (isa<Constant>(V))			if (isa<Constant>(V))
	return OrZero ? match(V, m_Power2OrZero()) : match(V, m_Power2());			return OrZero ? match(V, m_Power2OrZero()) : match(V, m_Power2());

				// i1 is by definition a power of 2 or zero.
				if (OrZero && V->getType()->getScalarSizeInBits() == 1)
				return true;

	auto *I = dyn_cast<Instruction>(V);			auto *I = dyn_cast<Instruction>(V);
	if (!I)			if (!I)
	return false;			return false;

	if (Q.CxtI && match(V, m_VScale())) {			if (Q.CxtI && match(V, m_VScale())) {
	const Function *F = Q.CxtI->getFunction();			const Function *F = Q.CxtI->getFunction();
	// The vscale_range indicates vscale is a power-of-two.			// The vscale_range indicates vscale is a power-of-two.
	return F->hasFnAttribute(Attribute::VScaleRange);			return F->hasFnAttribute(Attribute::VScaleRange);
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llvm/test/Analysis/ValueTracking/known-power-of-two.ll

Show First 20 Lines • Show All 613 Lines • ▼ Show 20 Lines	;
%r = icmp eq i16 %and, %xx		%r = icmp eq i16 %and, %xx
ret i1 %r		ret i1 %r
}		}

define i16 @i1_is_pow2_or_zero(i1 %x, i16 %y) {		define i16 @i1_is_pow2_or_zero(i1 %x, i16 %y) {
; CHECK-LABEL: define i16 @i1_is_pow2_or_zero		; CHECK-LABEL: define i16 @i1_is_pow2_or_zero
; CHECK-SAME: (i1 [[X:%.]], i16 [[Y:%.]]) {		; CHECK-SAME: (i1 [[X:%.]], i16 [[Y:%.]]) {
; CHECK-NEXT: [[XX:%.*]] = zext i1 [[X]] to i16		; CHECK-NEXT: [[XX:%.*]] = zext i1 [[X]] to i16
; CHECK-NEXT: [[YY:%.*]] = xor i16 [[XX]], [[Y]]		; CHECK-NEXT: [[R:%.*]] = or i16 [[XX]], [[Y]]
; CHECK-NEXT: [[R:%.*]] = call i16 @llvm.umax.i16(i16 [[YY]], i16 [[Y]])
; CHECK-NEXT: ret i16 [[R]]		; CHECK-NEXT: ret i16 [[R]]
;		;
%xx = zext i1 %x to i16		%xx = zext i1 %x to i16
%yy = xor i16 %y, %xx		%yy = xor i16 %y, %xx
%r = call i16 @llvm.umax.i16(i16 %yy, i16 %y)		%r = call i16 @llvm.umax.i16(i16 %yy, i16 %y)
ret i16 %r		ret i16 %r
}		}

define i16 @i1_is_pow2_or_zero2(i1 %x, i16 %y0, i16 %z) {		define i16 @i1_is_pow2_or_zero2(i1 %x, i16 %y0, i16 %z) {
; CHECK-LABEL: define i16 @i1_is_pow2_or_zero2		; CHECK-LABEL: define i16 @i1_is_pow2_or_zero2
; CHECK-SAME: (i1 [[X:%.]], i16 [[Y0:%.]], i16 [[Z:%.*]]) {		; CHECK-SAME: (i1 [[X:%.]], i16 [[Y0:%.]], i16 [[Z:%.*]]) {
; CHECK-NEXT: [[XX:%.*]] = zext i1 [[X]] to i16		; CHECK-NEXT: [[XX:%.*]] = zext i1 [[X]] to i16
; CHECK-NEXT: [[Y:%.*]] = or i16 [[Y0]], [[Z]]		; CHECK-NEXT: [[Y:%.*]] = or i16 [[Y0]], [[Z]]
; CHECK-NEXT: [[YY:%.*]] = xor i16 [[Y]], [[XX]]		; CHECK-NEXT: [[R:%.*]] = or i16 [[Y]], [[XX]]
; CHECK-NEXT: [[R:%.*]] = call i16 @llvm.umax.i16(i16 [[YY]], i16 [[Y]])
; CHECK-NEXT: ret i16 [[R]]		; CHECK-NEXT: ret i16 [[R]]
;		;
%xx = zext i1 %x to i16		%xx = zext i1 %x to i16
%y = or i16 %y0, %z		%y = or i16 %y0, %z
%yy = xor i16 %y, %xx		%yy = xor i16 %y, %xx
%r = call i16 @llvm.umax.i16(i16 %yy, i16 %y)		%r = call i16 @llvm.umax.i16(i16 %yy, i16 %y)
ret i16 %r		ret i16 %r
}		}

This is an archive of the discontinued LLVM Phabricator instance.

[ValueTracking] In `isKnownToBeAPowerOfTwo` an `i1` value is always true if `OrZero` is setClosedPublic

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Diff 548747

llvm/lib/Analysis/ValueTracking.cpp

llvm/test/Analysis/ValueTracking/known-power-of-two.ll

[ValueTracking] In `isKnownToBeAPowerOfTwo` an `i1` value is always true if `OrZero` is set
ClosedPublic