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InferAddressSpaces: Fix assert with unreachable code
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Authored by arsenm on Sep 15 2020, 11:14 AM.

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Reviewers

hliao
tra
jdoerfert
yaxunl
rampitec

Summary

Invalid IR in unreachable code is technically valid IR. In this case,
the address space of the value was never inferred, and we tried to
rewrite it with an invalid address space value which would assert.

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Event Timeline

arsenm created this revision.Sep 15 2020, 11:14 AM

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arsenm requested review of this revision.Sep 15 2020, 11:14 AM

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Add a test with a phi referencing itself just in case, although this worked before

LGTM

This revision is now accepted and ready to land.Sep 15 2020, 11:24 AM

tra accepted this revision.Sep 15 2020, 11:33 AM

LGTM

7d6ca2ec57073b9eabe6808ff1fe0560586c5ffb

Revision Contents

Path

Size

llvm/

lib/

Transforms/

Scalar/

InferAddressSpaces.cpp

6 lines

test/

Transforms/

InferAddressSpaces/

AMDGPU/

unreachable-code-assert.ll

27 lines

Diff 291978

llvm/lib/Transforms/Scalar/InferAddressSpaces.cpp

Show First 20 Lines • Show All 991 Lines • ▼ Show 20 Lines	bool InferAddressSpaces::rewriteWithNewAddressSpaces(
// For each address expression to be modified, creates a clone of it with its		// For each address expression to be modified, creates a clone of it with its
// pointer operands converted to the new address space. Since the pointer		// pointer operands converted to the new address space. Since the pointer
// operands are converted, the clone is naturally in the new address space by		// operands are converted, the clone is naturally in the new address space by
// construction.		// construction.
ValueToValueMapTy ValueWithNewAddrSpace;		ValueToValueMapTy ValueWithNewAddrSpace;
SmallVector<const Use *, 32> UndefUsesToFix;		SmallVector<const Use *, 32> UndefUsesToFix;
for (Value* V : Postorder) {		for (Value* V : Postorder) {
unsigned NewAddrSpace = InferredAddrSpace.lookup(V);		unsigned NewAddrSpace = InferredAddrSpace.lookup(V);

		// In some degenerate cases (e.g. invalid IR in unreachable code), we may
		// not even infer the value to have its original address space.
		if (NewAddrSpace == UninitializedAddressSpace)
		continue;

if (V->getType()->getPointerAddressSpace() != NewAddrSpace) {		if (V->getType()->getPointerAddressSpace() != NewAddrSpace) {
Value *New = cloneValueWithNewAddressSpace(		Value *New = cloneValueWithNewAddressSpace(
V, NewAddrSpace, ValueWithNewAddrSpace, &UndefUsesToFix);		V, NewAddrSpace, ValueWithNewAddrSpace, &UndefUsesToFix);
if (New)		if (New)
ValueWithNewAddrSpace[V] = New;		ValueWithNewAddrSpace[V] = New;
}		}
}		}

▲ Show 20 Lines • Show All 146 Lines • Show Last 20 Lines

llvm/test/Transforms/InferAddressSpaces/AMDGPU/unreachable-code-assert.ll

This file was added.

				; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
				; RUN: opt -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 -S -infer-address-spaces %s \| FileCheck %s

				define amdgpu_kernel void @subclass_data_assert() {
				; CHECK-LABEL: @subclass_data_assert(
				; CHECK-NEXT: entry:
				; CHECK-NEXT: unreachable
				; CHECK: strlen.while11:
				; CHECK-NEXT: [[I:%.]] = getelementptr i8, i8 [[I]], i64 1
				; CHECK-NEXT: [[I1:%.]] = load i8, i8 [[I]], align 1
				; CHECK-NEXT: [[I2:%.*]] = icmp eq i8 [[I1]], 0
				; CHECK-NEXT: br i1 [[I2]], label [[STRLEN_WHILE_DONE12:%.]], label [[STRLEN_WHILE11:%.]]
				; CHECK: strlen.while.done12:
				; CHECK-NEXT: ret void
				;
				entry:
				unreachable

				strlen.while11: ; preds = %strlen.while11
				%i = getelementptr i8, i8* %i, i64 1
				%i1 = load i8, i8* %i, align 1
				%i2 = icmp eq i8 %i1, 0
				br i1 %i2, label %strlen.while.done12, label %strlen.while11

				strlen.while.done12: ; preds = %strlen.while11
				ret void
				}