[llvm] [BPF] improve error handling by custom lowering & fail() (PR #75088)
Yingchi Long via llvm-commits
llvm-commits at lists.llvm.org
Tue Dec 12 21:35:11 PST 2023
https://github.com/inclyc updated https://github.com/llvm/llvm-project/pull/75088
>From 63661ffa74e941054d002a7922954250dfcc2447 Mon Sep 17 00:00:00 2001
From: Yingchi Long <i at lyc.dev>
Date: Tue, 12 Dec 2023 03:27:49 +0800
Subject: [PATCH 1/2] [BPF] improve error handling for unsupported sdiv, srem
Currently on mcpu=v3 we do not support sdiv, srem instructions.
And the backend crashes with stacktrace & coredump, which is misleading
for end users, as this is not a "bug"
Add llvm bug reporting for sdiv/srem on ISel legalize-op phase.
For clang frontend we can get detailed location & bug report.
$ build/bin/clang -g -target bpf -c local/sdiv.c
local/sdiv.c:1:35: error: unsupported signed division, please convert to unsigned div/mod.
1 | int sdiv(int a, int b) { return a / b; }
| ^
1 error generated.
Fixes: #70433
Fixes: #48647
This also improves error handling for dynamic stack allocation:
local/vla.c:2:3: error: unsupported dynamic stack allocation
2 | int b[n];
| ^
1 error generated.
Fixes: #57171
---
llvm/lib/Target/BPF/BPFISelDAGToDAG.cpp | 14 -------------
llvm/lib/Target/BPF/BPFISelLowering.cpp | 26 ++++++++++++++++++++++---
llvm/lib/Target/BPF/BPFISelLowering.h | 2 ++
llvm/test/CodeGen/BPF/dynamic-stack.ll | 8 ++++++++
llvm/test/CodeGen/BPF/sdiv_error.ll | 4 ++--
5 files changed, 35 insertions(+), 19 deletions(-)
create mode 100644 llvm/test/CodeGen/BPF/dynamic-stack.ll
diff --git a/llvm/lib/Target/BPF/BPFISelDAGToDAG.cpp b/llvm/lib/Target/BPF/BPFISelDAGToDAG.cpp
index b0cfca3b7ab66a..909c7c005735b6 100644
--- a/llvm/lib/Target/BPF/BPFISelDAGToDAG.cpp
+++ b/llvm/lib/Target/BPF/BPFISelDAGToDAG.cpp
@@ -192,20 +192,6 @@ void BPFDAGToDAGISel::Select(SDNode *Node) {
switch (Opcode) {
default:
break;
- case ISD::SDIV: {
- if (!Subtarget->hasSdivSmod()) {
- DebugLoc Empty;
- const DebugLoc &DL = Node->getDebugLoc();
- if (DL != Empty)
- errs() << "Error at line " << DL.getLine() << ": ";
- else
- errs() << "Error: ";
- errs() << "Unsupport signed division for DAG: ";
- Node->print(errs(), CurDAG);
- errs() << "Please convert to unsigned div/mod.\n";
- }
- break;
- }
case ISD::INTRINSIC_W_CHAIN: {
unsigned IntNo = cast<ConstantSDNode>(Node->getOperand(1))->getZExtValue();
switch (IntNo) {
diff --git a/llvm/lib/Target/BPF/BPFISelLowering.cpp b/llvm/lib/Target/BPF/BPFISelLowering.cpp
index f3368b8979d6f5..2fe86e75ddae8f 100644
--- a/llvm/lib/Target/BPF/BPFISelLowering.cpp
+++ b/llvm/lib/Target/BPF/BPFISelLowering.cpp
@@ -99,8 +99,10 @@ BPFTargetLowering::BPFTargetLowering(const TargetMachine &TM,
setOperationAction(ISD::SDIVREM, VT, Expand);
setOperationAction(ISD::UDIVREM, VT, Expand);
- if (!STI.hasSdivSmod())
- setOperationAction(ISD::SREM, VT, Expand);
+ if (!STI.hasSdivSmod()) {
+ setOperationAction(ISD::SDIV, VT, Custom);
+ setOperationAction(ISD::SREM, VT, Custom);
+ }
setOperationAction(ISD::MULHU, VT, Expand);
setOperationAction(ISD::MULHS, VT, Expand);
setOperationAction(ISD::UMUL_LOHI, VT, Expand);
@@ -307,8 +309,11 @@ SDValue BPFTargetLowering::LowerOperation(SDValue Op, SelectionDAG &DAG) const {
return LowerGlobalAddress(Op, DAG);
case ISD::SELECT_CC:
return LowerSELECT_CC(Op, DAG);
+ case ISD::SDIV:
+ case ISD::SREM:
+ return LowerSDIVSREM(Op, DAG);
case ISD::DYNAMIC_STACKALLOC:
- report_fatal_error("unsupported dynamic stack allocation");
+ return LowerDYNAMIC_STACKALLOC(Op, DAG);
}
}
@@ -617,6 +622,21 @@ static void NegateCC(SDValue &LHS, SDValue &RHS, ISD::CondCode &CC) {
}
}
+SDValue BPFTargetLowering::LowerSDIVSREM(SDValue Op, SelectionDAG &DAG) const {
+ SDLoc DL(Op);
+ fail(DL, DAG,
+ "unsupported signed division, please convert to unsigned div/mod.");
+ return DAG.getUNDEF(Op->getValueType(0));
+}
+
+SDValue BPFTargetLowering::LowerDYNAMIC_STACKALLOC(SDValue Op,
+ SelectionDAG &DAG) const {
+ SDLoc DL(Op);
+ fail(DL, DAG, "unsupported dynamic stack allocation");
+ auto Ops = {DAG.getConstant(0, SDLoc(), Op.getValueType()), Op.getOperand(0)};
+ return DAG.getMergeValues(Ops, SDLoc());
+}
+
SDValue BPFTargetLowering::LowerBR_CC(SDValue Op, SelectionDAG &DAG) const {
SDValue Chain = Op.getOperand(0);
ISD::CondCode CC = cast<CondCodeSDNode>(Op.getOperand(1))->get();
diff --git a/llvm/lib/Target/BPF/BPFISelLowering.h b/llvm/lib/Target/BPF/BPFISelLowering.h
index 3be1c04bca3d65..819711b650c15f 100644
--- a/llvm/lib/Target/BPF/BPFISelLowering.h
+++ b/llvm/lib/Target/BPF/BPFISelLowering.h
@@ -73,6 +73,8 @@ class BPFTargetLowering : public TargetLowering {
bool HasJmpExt;
bool HasMovsx;
+ SDValue LowerSDIVSREM(SDValue Op, SelectionDAG &DAG) const;
+ SDValue LowerDYNAMIC_STACKALLOC(SDValue Op, SelectionDAG &DAG) const;
SDValue LowerBR_CC(SDValue Op, SelectionDAG &DAG) const;
SDValue LowerSELECT_CC(SDValue Op, SelectionDAG &DAG) const;
SDValue LowerGlobalAddress(SDValue Op, SelectionDAG &DAG) const;
diff --git a/llvm/test/CodeGen/BPF/dynamic-stack.ll b/llvm/test/CodeGen/BPF/dynamic-stack.ll
new file mode 100644
index 00000000000000..046523ded8001c
--- /dev/null
+++ b/llvm/test/CodeGen/BPF/dynamic-stack.ll
@@ -0,0 +1,8 @@
+; RUN: not llc < %s -mtriple=bpfel 2>&1 | FileCheck %s
+
+define i64 @vla(i64 %num) {
+; CHECK: unsupported dynamic stack allocation
+ %vla = alloca i32, i64 %num
+ %ret = ptrtoint ptr %vla to i64
+ ret i64 %ret
+}
diff --git a/llvm/test/CodeGen/BPF/sdiv_error.ll b/llvm/test/CodeGen/BPF/sdiv_error.ll
index fc79a1d44c16ba..d256d054bbceb2 100644
--- a/llvm/test/CodeGen/BPF/sdiv_error.ll
+++ b/llvm/test/CodeGen/BPF/sdiv_error.ll
@@ -1,6 +1,6 @@
-; RUN: not --crash llc -march=bpf < %s 2> %t1
+; RUN: not llc -march=bpf < %s 2> %t1
; RUN: FileCheck %s < %t1
-; CHECK: Unsupport signed division
+; CHECK: unsupported signed division
; Function Attrs: norecurse nounwind readnone
define i32 @test(i32 %len) #0 {
>From a5c660756c58d23e7d5dce3b2091d301c37fc364 Mon Sep 17 00:00:00 2001
From: Yingchi Long <i at lyc.dev>
Date: Wed, 13 Dec 2023 13:33:55 +0800
Subject: [PATCH 2/2] [BPF] add sdiv_error test
---
llvm/test/CodeGen/BPF/sdiv_error.ll | 4 ++--
llvm/test/CodeGen/BPF/srem_error.ll | 9 +++++++++
2 files changed, 11 insertions(+), 2 deletions(-)
create mode 100644 llvm/test/CodeGen/BPF/srem_error.ll
diff --git a/llvm/test/CodeGen/BPF/sdiv_error.ll b/llvm/test/CodeGen/BPF/sdiv_error.ll
index d256d054bbceb2..b2b5b749ee648e 100644
--- a/llvm/test/CodeGen/BPF/sdiv_error.ll
+++ b/llvm/test/CodeGen/BPF/sdiv_error.ll
@@ -1,9 +1,9 @@
-; RUN: not llc -march=bpf < %s 2> %t1
+; RUN: not llc -mtriple=bpf < %s 2> %t1
; RUN: FileCheck %s < %t1
; CHECK: unsupported signed division
; Function Attrs: norecurse nounwind readnone
define i32 @test(i32 %len) #0 {
- %1 = srem i32 %len, 15
+ %1 = sdiv i32 %len, 15
ret i32 %1
}
diff --git a/llvm/test/CodeGen/BPF/srem_error.ll b/llvm/test/CodeGen/BPF/srem_error.ll
new file mode 100644
index 00000000000000..2e6105add992db
--- /dev/null
+++ b/llvm/test/CodeGen/BPF/srem_error.ll
@@ -0,0 +1,9 @@
+; RUN: not llc -mtriple=bpf < %s 2> %t1
+; RUN: FileCheck %s < %t1
+; CHECK: unsupported signed division
+
+; Function Attrs: norecurse nounwind readnone
+define i32 @test(i32 %len) #0 {
+ %1 = srem i32 %len, 15
+ ret i32 %1
+}
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