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[AMDGPU] Split entry basic block after alloca instructions.

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While initializing the LDS pointers within entry basic block of kernel(s), make
sure that the entry basic block is split after alloca instructions.

Reviewed By: rampitec

Differential Revision: https://reviews.llvm.org/D108971
This commit is contained in:
hsmahesha 2021-09-01 10:18:21 +05:30
parent 6a75041a16
commit 98f4713122
2 changed files with 73 additions and 3 deletions
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15
llvm/lib/Target/AMDGPU/AMDGPUReplaceLDSUseWithPointer.cpp
View file

@ -191,10 +191,19 @@ class ReplaceLDSUseImpl {
if (!BasicBlockEntry.second)
return BasicBlockEntry.first->second;
// Split entry basic block of kernel K.
auto *EI = &(*(K->getEntryBlock().getFirstInsertionPt()));
IRBuilder<> Builder(EI);
// Split entry basic block of kernel K just after alloca.
//
// Find the split point just after alloca.
auto &EBB = K->getEntryBlock();
auto *EI = &(*(EBB.getFirstInsertionPt()));
BasicBlock::reverse_iterator RIT(EBB.getTerminator());
while (!isa<AllocaInst>(*RIT) && (&*RIT != EI))
++RIT;
if (isa<AllocaInst>(*RIT))
--RIT;
// Split entry basic block.
IRBuilder<> Builder(&*RIT);
Value *Mbcnt =
Builder.CreateIntrinsic(Intrinsic::amdgcn_mbcnt_lo, {},
{Builder.getInt32(-1), Builder.getInt32(0)});

61
llvm/test/CodeGen/AMDGPU/replace-lds-by-ptr-split-entry-bb-after-alloca.ll Normal file
View file

@ -0,0 +1,61 @@
; RUN: opt -S -mtriple=amdgcn-- -amdgpu-replace-lds-use-with-pointer -amdgpu-enable-lds-replace-with-pointer=true < %s | FileCheck %s
; DESCRIPTION:
;
; There is one lds global defined here, and this lds is used within a single non-kernel
; function, as an operand of nested constant expression, and this non-kernel function is
; reachable from kernel. Hence nested constant expression should to be converted into a
; series of instructons and pointer replacement should take place.
;
; Further the entry basic block of the kernel @k0 contains alloca instruction. Hence the
; entry basic splitting for pointer initialization should happen after alloca.
;
; Original LDS should exist.
; CHECK: @used_only_within_func = addrspace(3) global [4 x i32] undef, align 4
@used_only_within_func = addrspace(3) global [4 x i32] undef, align 4
; Pointers should be created.
; CHECK: @used_only_within_func.ptr = internal unnamed_addr addrspace(3) global i16 undef, align 2
; Pointer replacement code should be added.
define void @f0(i32 %x) {
; CHECK-LABEL: entry:
; CHECK: %0 = load i16, i16 addrspace(3)* @used_only_within_func.ptr, align 2
; CHECK: %1 = getelementptr i8, i8 addrspace(3)* null, i16 %0
; CHECK: %2 = bitcast i8 addrspace(3)* %1 to [4 x i32] addrspace(3)*
; CHECK: %3 = getelementptr inbounds [4 x i32], [4 x i32] addrspace(3)* %2, i32 0, i32 0
; CHECK: %4 = addrspacecast i32 addrspace(3)* %3 to i32*
; CHECK: %5 = ptrtoint i32* %4 to i64
; CHECK: %6 = add i64 %5, %5
; CHECK: %7 = inttoptr i64 %6 to i32*
; CHECK: store i32 %x, i32* %7, align 4
; CHECK: ret void
entry:
store i32 %x, i32* inttoptr (i64 add (i64 ptrtoint (i32* addrspacecast (i32 addrspace(3)* bitcast ([4 x i32] addrspace(3)* @used_only_within_func to i32 addrspace(3)*) to i32*) to i64), i64 ptrtoint (i32* addrspacecast (i32 addrspace(3)* bitcast ([4 x i32] addrspace(3)* @used_only_within_func to i32 addrspace(3)*) to i32*) to i64)) to i32*), align 4
ret void
}
; Pointer initialization code shoud be added
define amdgpu_kernel void @k0() {
; CHECK-LABEL: entry:
; CHECK: %0 = alloca i64, align 8, addrspace(5)
; CHECK: %1 = call i32 @llvm.amdgcn.mbcnt.lo(i32 -1, i32 0)
; CHECK: %2 = icmp eq i32 %1, 0
; CHECK: br i1 %2, label %3, label %4
;
; CHECK-LABEL: 3:
; CHECK: store i16 ptrtoint ([4 x i32] addrspace(3)* @used_only_within_func to i16), i16 addrspace(3)* @used_only_within_func.ptr, align 2
; CHECK: br label %4
; CHECK-LABEL: 4:
; CHECK: call void @llvm.amdgcn.wave.barrier()
; CHECK: %5 = addrspacecast i64 addrspace(5)* %0 to i64*
; CHECK: call void @f0(i32 0)
; CHECK: ret void
entry:
%0 = alloca i64, align 8, addrspace(5)
%1 = addrspacecast i64 addrspace(5)* %0 to i64*
call void @f0(i32 0)
ret void
}