[llvm] AMDGPU: Return legal addressmode correctly for flat scratch (PR #71494)
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Mon Dec 4 19:22:12 PST 2023
https://github.com/ruiling updated https://github.com/llvm/llvm-project/pull/71494
>From a81838e6f2c7cef6b80b839a0f1005a94e70f6a1 Mon Sep 17 00:00:00 2001
From: Ruiling Song <ruiling.song at amd.com>
Date: Mon, 6 Nov 2023 09:32:03 +0800
Subject: [PATCH] AMDGPU: Return legal addressmode correctly for flat scratch
---
llvm/lib/Target/AMDGPU/SIISelLowering.cpp | 44 ++++++++++---------
llvm/lib/Target/AMDGPU/SIISelLowering.h | 3 +-
.../CodeGen/AMDGPU/scratch-pointer-sink.ll | 5 +--
3 files changed, 28 insertions(+), 24 deletions(-)
diff --git a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
index 53ab5da013539..a7f4d63229b7e 100644
--- a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
@@ -1322,7 +1322,9 @@ bool SITargetLowering::getAddrModeArguments(IntrinsicInst *II,
}
}
-bool SITargetLowering::isLegalFlatAddressingMode(const AddrMode &AM) const {
+bool SITargetLowering::isLegalFlatAddressingMode(const AddrMode &AM,
+ unsigned AddrSpace,
+ uint64_t FlatVariant) const {
if (!Subtarget->hasFlatInstOffsets()) {
// Flat instructions do not have offsets, and only have the register
// address.
@@ -1330,29 +1332,27 @@ bool SITargetLowering::isLegalFlatAddressingMode(const AddrMode &AM) const {
}
return AM.Scale == 0 &&
- (AM.BaseOffs == 0 ||
- Subtarget->getInstrInfo()->isLegalFLATOffset(
- AM.BaseOffs, AMDGPUAS::FLAT_ADDRESS, SIInstrFlags::FLAT));
+ (AM.BaseOffs == 0 || Subtarget->getInstrInfo()->isLegalFLATOffset(
+ AM.BaseOffs, AddrSpace, FlatVariant));
}
bool SITargetLowering::isLegalGlobalAddressingMode(const AddrMode &AM) const {
if (Subtarget->hasFlatGlobalInsts())
- return AM.Scale == 0 &&
- (AM.BaseOffs == 0 || Subtarget->getInstrInfo()->isLegalFLATOffset(
- AM.BaseOffs, AMDGPUAS::GLOBAL_ADDRESS,
- SIInstrFlags::FlatGlobal));
+ return isLegalFlatAddressingMode(AM, AMDGPUAS::GLOBAL_ADDRESS,
+ SIInstrFlags::FlatGlobal);
if (!Subtarget->hasAddr64() || Subtarget->useFlatForGlobal()) {
- // Assume the we will use FLAT for all global memory accesses
- // on VI.
- // FIXME: This assumption is currently wrong. On VI we still use
- // MUBUF instructions for the r + i addressing mode. As currently
- // implemented, the MUBUF instructions only work on buffer < 4GB.
- // It may be possible to support > 4GB buffers with MUBUF instructions,
- // by setting the stride value in the resource descriptor which would
- // increase the size limit to (stride * 4GB). However, this is risky,
- // because it has never been validated.
- return isLegalFlatAddressingMode(AM);
+ // Assume the we will use FLAT for all global memory accesses
+ // on VI.
+ // FIXME: This assumption is currently wrong. On VI we still use
+ // MUBUF instructions for the r + i addressing mode. As currently
+ // implemented, the MUBUF instructions only work on buffer < 4GB.
+ // It may be possible to support > 4GB buffers with MUBUF instructions,
+ // by setting the stride value in the resource descriptor which would
+ // increase the size limit to (stride * 4GB). However, this is risky,
+ // because it has never been validated.
+ return isLegalFlatAddressingMode(AM, AMDGPUAS::FLAT_ADDRESS,
+ SIInstrFlags::FLAT);
}
return isLegalMUBUFAddressingMode(AM);
@@ -1449,7 +1449,10 @@ bool SITargetLowering::isLegalAddressingMode(const DataLayout &DL,
}
if (AS == AMDGPUAS::PRIVATE_ADDRESS)
- return isLegalMUBUFAddressingMode(AM);
+ return Subtarget->enableFlatScratch()
+ ? isLegalFlatAddressingMode(AM, AMDGPUAS::PRIVATE_ADDRESS,
+ SIInstrFlags::FlatScratch)
+ : isLegalMUBUFAddressingMode(AM);
if (AS == AMDGPUAS::LOCAL_ADDRESS ||
(AS == AMDGPUAS::REGION_ADDRESS && Subtarget->hasGDS())) {
@@ -1475,7 +1478,8 @@ bool SITargetLowering::isLegalAddressingMode(const DataLayout &DL,
// computation. We don't have instructions that compute pointers with any
// addressing modes, so treat them as having no offset like flat
// instructions.
- return isLegalFlatAddressingMode(AM);
+ return isLegalFlatAddressingMode(AM, AMDGPUAS::FLAT_ADDRESS,
+ SIInstrFlags::FLAT);
}
// Assume a user alias of global for unknown address spaces.
diff --git a/llvm/lib/Target/AMDGPU/SIISelLowering.h b/llvm/lib/Target/AMDGPU/SIISelLowering.h
index 746a88c5ea13a..c9cc149218a99 100644
--- a/llvm/lib/Target/AMDGPU/SIISelLowering.h
+++ b/llvm/lib/Target/AMDGPU/SIISelLowering.h
@@ -221,7 +221,8 @@ class SITargetLowering final : public AMDGPUTargetLowering {
SDValue performClampCombine(SDNode *N, DAGCombinerInfo &DCI) const;
SDValue performRcpCombine(SDNode *N, DAGCombinerInfo &DCI) const;
- bool isLegalFlatAddressingMode(const AddrMode &AM) const;
+ bool isLegalFlatAddressingMode(const AddrMode &AM, unsigned AddrSpace,
+ uint64_t FlatVariant) const;
bool isLegalMUBUFAddressingMode(const AddrMode &AM) const;
unsigned isCFIntrinsic(const SDNode *Intr) const;
diff --git a/llvm/test/CodeGen/AMDGPU/scratch-pointer-sink.ll b/llvm/test/CodeGen/AMDGPU/scratch-pointer-sink.ll
index d0078bfb34b3f..4987664dae022 100644
--- a/llvm/test/CodeGen/AMDGPU/scratch-pointer-sink.ll
+++ b/llvm/test/CodeGen/AMDGPU/scratch-pointer-sink.ll
@@ -6,16 +6,15 @@ define amdgpu_gfx i32 @sink_scratch_pointer(ptr addrspace(5) %stack, i32 inreg %
; GCN-LABEL: sink_scratch_pointer:
; GCN: ; %bb.0:
; GCN-NEXT: s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; GCN-NEXT: v_add_nc_u32_e32 v0, -4, v0
; GCN-NEXT: s_cmp_lg_u32 s4, 0
; GCN-NEXT: s_cbranch_scc0 .LBB0_2
; GCN-NEXT: ; %bb.1: ; %bb2
-; GCN-NEXT: scratch_load_b32 v0, v0, off
+; GCN-NEXT: scratch_load_b32 v0, v0, off offset:-4
; GCN-NEXT: s_waitcnt vmcnt(0)
; GCN-NEXT: s_setpc_b64 s[30:31]
; GCN-NEXT: .LBB0_2: ; %bb1
; GCN-NEXT: v_mov_b32_e32 v1, 1
-; GCN-NEXT: scratch_store_b32 v0, v1, off
+; GCN-NEXT: scratch_store_b32 v0, v1, off offset:-4
; GCN-NEXT: v_mov_b32_e32 v0, 0
; GCN-NEXT: s_setpc_b64 s[30:31]
;
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