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GlobalISel: don't emit degenerate G_INSERT instructions.

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Before, we were producing G_INSERT instructions that were actually closer to a
cast or even a COPY when both input and output sizes are the same. This doesn't
really make sense and means that everything interpreting a G_INSERT also has to
handle all these kinds of casts.

So now we detect these degenerate cases and emit real casts instead.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297051 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Tim Northover 2017-03-06 19:04:17 +00:00
parent f0a0c2348e
commit ca62919afb
3 changed files with 48 additions and 0 deletions
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3
include/llvm/CodeGen/GlobalISel/MachineIRBuilder.h
View File

@ -338,6 +338,9 @@ public:
/// \return The newly created instruction.
MachineInstrBuilder buildZExtOrTrunc(unsigned Res, unsigned Op);
/// Build and insert an appropriate cast between two registers of equal size.
MachineInstrBuilder buildCast(unsigned Dst, unsigned Src);
/// Build and insert G_BR \p Dest
///
/// G_BR is an unconditional branch to \p Dest.

25
lib/CodeGen/GlobalISel/MachineIRBuilder.cpp
View File

@ -362,6 +362,26 @@ MachineInstrBuilder MachineIRBuilder::buildZExtOrTrunc(unsigned Res,
return buildInstr(Opcode).addDef(Res).addUse(Op);
}
MachineInstrBuilder MachineIRBuilder::buildCast(unsigned Dst, unsigned Src) {
LLT SrcTy = MRI->getType(Src);
LLT DstTy = MRI->getType(Dst);
if (SrcTy == DstTy)
return buildCopy(Dst, Src);
unsigned Opcode;
if (SrcTy.isPointer() && DstTy.isScalar())
Opcode = TargetOpcode::G_PTRTOINT;
else if (DstTy.isPointer() && SrcTy.isScalar())
Opcode = TargetOpcode::G_INTTOPTR;
else {
assert(!SrcTy.isPointer() && !DstTy.isPointer() && "n G_ADDRCAST yet");
Opcode = TargetOpcode::G_BITCAST;
}
return buildInstr(Opcode).addDef(Dst).addUse(Src);
}
MachineInstrBuilder MachineIRBuilder::buildExtract(ArrayRef<unsigned> Results,
ArrayRef<uint64_t> Indices,
unsigned Src) {
@ -462,6 +482,11 @@ MachineInstrBuilder MachineIRBuilder::buildUnmerge(ArrayRef<unsigned> Res,
MachineInstrBuilder MachineIRBuilder::buildInsert(unsigned Res, unsigned Src,
unsigned Op, unsigned Index) {
if (MRI->getType(Res).getSizeInBits() == MRI->getType(Op).getSizeInBits()) {
assert(Index == 0 && "insertion past the end of a register");
return buildCast(Res, Op);
}
return buildInstr(TargetOpcode::G_INSERT)
.addDef(Res)
.addUse(Src)

20
test/CodeGen/AArch64/GlobalISel/arm64-irtranslator.ll
View File

@ -890,6 +890,26 @@ define void @test_insertvalue(%struct.nested* %addr, i32 %val) {
ret void
}
define [1 x i64] @test_trivial_insert([1 x i64] %s, i64 %val) {
; CHECK-LABEL: name: test_trivial_insert
; CHECK: [[STRUCT:%[0-9]+]](s64) = COPY %x0
; CHECK: [[VAL:%[0-9]+]](s64) = COPY %x1
; CHECK: [[RES:%[0-9]+]](s64) = COPY [[VAL]](s64)
; CHECK: %x0 = COPY [[RES]]
%res = insertvalue [1 x i64] %s, i64 %val, 0
ret [1 x i64] %res
}
define [1 x i8*] @test_trivial_insert_ptr([1 x i8*] %s, i8* %val) {
; CHECK-LABEL: name: test_trivial_insert_ptr
; CHECK: [[STRUCT:%[0-9]+]](s64) = COPY %x0
; CHECK: [[VAL:%[0-9]+]](p0) = COPY %x1
; CHECK: [[RES:%[0-9]+]](s64) = G_PTRTOINT [[VAL]](p0)
; CHECK: %x0 = COPY [[RES]]
%res = insertvalue [1 x i8*] %s, i8* %val, 0
ret [1 x i8*] %res
}
; CHECK-LABEL: name: test_insertvalue_agg
; CHECK: [[SMALLSTRUCT:%[0-9]+]](s64) = G_LOAD
; CHECK: [[STRUCT:%[0-9]+]](s128) = G_LOAD