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[mlir][LLVMIR] Do not cache llvm::Constant into instMap 

Constants in MLIR are not globally unique, unlike that in LLVM IR.
Therefore, reusing previous-translated constants might cause the user
operations not being dominated by the constant (because the
previous-translated ones can be placed in arbitrary place)

This indeed misses some opportunities where we actually can reuse a
previous-translated constants, but verbosity is not our first priority
here.

Differential Revision: https://reviews.llvm.org/D124404
This commit is contained in:
Min-Yih Hsu 2022-04-20 10:40:37 -07:00
parent ea9bcb8b27
commit a75657d66a
2 changed files with 39 additions and 6 deletions
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11
mlir/lib/Target/LLVMIR/ConvertFromLLVMIR.cpp
View File

@ -465,15 +465,14 @@ Value Importer::processConstant(llvm::Constant *c) {
if (!type)
return nullptr;
if (auto symbolRef = attr.dyn_cast<FlatSymbolRefAttr>())
return instMap[c] = bEntry.create<AddressOfOp>(unknownLoc, type,
symbolRef.getValue());
return instMap[c] = bEntry.create<ConstantOp>(unknownLoc, type, attr);
return bEntry.create<AddressOfOp>(unknownLoc, type, symbolRef.getValue());
return bEntry.create<ConstantOp>(unknownLoc, type, attr);
}
if (auto *cn = dyn_cast<llvm::ConstantPointerNull>(c)) {
Type type = processType(cn->getType());
if (!type)
return nullptr;
return instMap[c] = bEntry.create<NullOp>(unknownLoc, type);
return bEntry.create<NullOp>(unknownLoc, type);
}
if (auto *gv = dyn_cast<llvm::GlobalVariable>(c))
return bEntry.create<AddressOfOp>(UnknownLoc::get(context),
@ -498,13 +497,13 @@ Value Importer::processConstant(llvm::Constant *c) {
// Remove this zombie LLVM instruction now, leaving us only with the MLIR
// op.
i->deleteValue();
return instMap[c] = value;
return value;
}
if (auto *ue = dyn_cast<llvm::UndefValue>(c)) {
Type type = processType(ue->getType());
if (!type)
return nullptr;
return instMap[c] = bEntry.create<UndefOp>(UnknownLoc::get(context), type);
return bEntry.create<UndefOp>(UnknownLoc::get(context), type);
}
if (isa<llvm::ConstantAggregate>(c) || isa<llvm::ConstantAggregateZero>(c)) {

34
mlir/test/Target/LLVMIR/Import/incorrect-constant-caching.ll Normal file
View File

@ -0,0 +1,34 @@
; RUN: mlir-translate --import-llvm %s | FileCheck %s
; Testing the fix for issue where llvm.getelementptr translated from the second
; ConstantExpr-GEP tried to use llvm.constant(0: i32)-s that were below itself,
; because it's reusing the cached ConstantInt-type zero value translated earlier.
; This test is primarily used to make sure an verification is passed. Thus, we
; only wrote minimum level of checks.
%my_struct = type {i32, i8*}
; CHECK: llvm.mlir.constant(0 : i32) : i32
; CHECK: llvm.mlir.constant(0 : i32) : i32
; CHECK: llvm.mlir.addressof @str1 : !llvm.ptr<array<5 x i8>>
; CHECK: llvm.getelementptr
; CHECK: llvm.mlir.constant(7 : i32) : i32
; CHECK: llvm.mlir.undef : !llvm.struct<"my_struct", (i32, ptr<i8>)>
; CHECK: llvm.insertvalue
; CHECK: llvm.insertvalue
; CHECK: llvm.mlir.constant(0 : i32) : i32
; CHECK: llvm.mlir.constant(0 : i32) : i32
; CHECK: llvm.mlir.addressof @str0 : !llvm.ptr<array<5 x i8>>
; CHECK: llvm.getelementptr
; CHECK: llvm.mlir.constant(8 : i32) : i32
; CHECK: llvm.mlir.undef : !llvm.struct<"my_struct", (i32, ptr<i8>)>
; CHECK: llvm.insertvalue
; CHECK: llvm.insertvalue
; CHECK: llvm.mlir.undef : !llvm.array<2 x struct<"my_struct", (i32, ptr<i8>)>>
; CHECK: llvm.insertvalue
; CHECK: llvm.insertvalue
; CHECK: llvm.return
@str0 = private unnamed_addr constant [5 x i8] c"aaaa\00"
@str1 = private unnamed_addr constant [5 x i8] c"bbbb\00"
@g = global [2 x %my_struct] [%my_struct {i32 8, i8* getelementptr ([5 x i8], [5 x i8]* @str0, i32 0, i32 0)}, %my_struct {i32 7, i8* getelementptr ([5 x i8], [5 x i8]* @str1, i32 0, i32 0)}]