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[SandboxVec][BottomUpVec] Add -sbvec-stop-at flag for debugging #129097

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Merged
merged 1 commit into from
Feb 27, 2025
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[SandboxVec][BottomUpVec] Add -sbvec-stop-at flag for debugging #129097

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3 changes: 3 additions & 0 deletions llvm/include/llvm/Transforms/Vectorize/SandboxVectorizer/Passes/BottomUpVec.h
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Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,9 @@ class BottomUpVec final : public RegionPass {
DenseSet<Instruction *> DeadInstrCandidates;
/// Maps scalars to vectors.
std::unique_ptr<InstrMaps> IMaps;
/// Counter used for force-stopping the vectorizer after this many
/// invocations. Used for debugging miscompiles.
unsigned long BottomUpInvocationCnt = 0;

/// Creates and returns a vector instruction that replaces the instructions in
/// \p Bndl. \p Operands are the already vectorized operands.
Expand Down
10 changes: 10 additions & 0 deletions llvm/lib/Transforms/Vectorize/SandboxVectorizer/Passes/BottomUpVec.cpp
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Expand Up @@ -25,6 +25,13 @@ static cl::opt<bool>
"emit new instructions (*very* expensive)."));
#endif // NDEBUG

static constexpr const unsigned long StopAtDisabled =
std::numeric_limits<unsigned long>::max();
static cl::opt<unsigned long>
StopAt("sbvec-stop-at", cl::init(StopAtDisabled), cl::Hidden,
cl::desc("Vectorize if the invocation count is < than this. 0 "
"disables vectorization."));

namespace sandboxir {

static SmallVector<Value *, 4> getOperand(ArrayRef<Value *> Bndl,
Expand Down Expand Up @@ -456,6 +463,9 @@ Value *BottomUpVec::emitVectors() {

bool BottomUpVec::tryVectorize(ArrayRef<Value *> Bndl) {
Change = false;
if (LLVM_UNLIKELY(BottomUpInvocationCnt++ >= StopAt &&
StopAt != StopAtDisabled))
return false;
DeadInstrCandidates.clear();
Legality->clear();
Actions.clear();
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61 changes: 61 additions & 0 deletions llvm/test/Transforms/SandboxVectorizer/stop_at.ll
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@@ -0,0 +1,61 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
; RUN: opt -passes=sandbox-vectorizer -sbvec-vec-reg-bits=1024 -sbvec-allow-non-pow2 -sbvec-passes="seed-collection<tr-save,bottom-up-vec,tr-accept>" --sbvec-stop-at=0 %s -S | FileCheck %s --check-prefix=STOPAT0
; RUN: opt -passes=sandbox-vectorizer -sbvec-vec-reg-bits=1024 -sbvec-allow-non-pow2 -sbvec-passes="seed-collection<tr-save,bottom-up-vec,tr-accept>" --sbvec-stop-at=1 %s -S | FileCheck %s --check-prefix=STOPAT1
; RUN: opt -passes=sandbox-vectorizer -sbvec-vec-reg-bits=1024 -sbvec-allow-non-pow2 -sbvec-passes="seed-collection<tr-save,bottom-up-vec,tr-accept>" --sbvec-stop-at=2 %s -S | FileCheck %s --check-prefix=STOPAT2

define void @widen(ptr %ptrA, ptr %ptrB) {
; STOPAT0-LABEL: define void @widen(
; STOPAT0-SAME: ptr [[PTRA:%.*]], ptr [[PTRB:%.*]]) {
; STOPAT0-NEXT: [[PTRA0:%.*]] = getelementptr float, ptr [[PTRA]], i32 0
; STOPAT0-NEXT: [[PTRA1:%.*]] = getelementptr float, ptr [[PTRA]], i32 1
; STOPAT0-NEXT: [[LDA0:%.*]] = load float, ptr [[PTRA0]], align 4
; STOPAT0-NEXT: [[LDA1:%.*]] = load float, ptr [[PTRA1]], align 4
; STOPAT0-NEXT: store float [[LDA0]], ptr [[PTRA0]], align 4
; STOPAT0-NEXT: store float [[LDA1]], ptr [[PTRA1]], align 4
; STOPAT0-NEXT: [[PTRB0:%.*]] = getelementptr float, ptr [[PTRB]], i32 0
; STOPAT0-NEXT: [[PTRB1:%.*]] = getelementptr float, ptr [[PTRB]], i32 1
; STOPAT0-NEXT: [[LDB0:%.*]] = load float, ptr [[PTRB0]], align 4
; STOPAT0-NEXT: [[LDB1:%.*]] = load float, ptr [[PTRB1]], align 4
; STOPAT0-NEXT: store float [[LDB0]], ptr [[PTRB0]], align 4
; STOPAT0-NEXT: store float [[LDB1]], ptr [[PTRB1]], align 4
; STOPAT0-NEXT: ret void
;
; STOPAT1-LABEL: define void @widen(
; STOPAT1-SAME: ptr [[PTRA:%.*]], ptr [[PTRB:%.*]]) {
; STOPAT1-NEXT: [[PTRA0:%.*]] = getelementptr float, ptr [[PTRA]], i32 0
; STOPAT1-NEXT: [[VECL:%.*]] = load <2 x float>, ptr [[PTRA0]], align 4
; STOPAT1-NEXT: store <2 x float> [[VECL]], ptr [[PTRA0]], align 4
; STOPAT1-NEXT: [[PTRB0:%.*]] = getelementptr float, ptr [[PTRB]], i32 0
; STOPAT1-NEXT: [[PTRB1:%.*]] = getelementptr float, ptr [[PTRB]], i32 1
; STOPAT1-NEXT: [[LDB0:%.*]] = load float, ptr [[PTRB0]], align 4
; STOPAT1-NEXT: [[LDB1:%.*]] = load float, ptr [[PTRB1]], align 4
; STOPAT1-NEXT: store float [[LDB0]], ptr [[PTRB0]], align 4
; STOPAT1-NEXT: store float [[LDB1]], ptr [[PTRB1]], align 4
; STOPAT1-NEXT: ret void
;
; STOPAT2-LABEL: define void @widen(
; STOPAT2-SAME: ptr [[PTRA:%.*]], ptr [[PTRB:%.*]]) {
; STOPAT2-NEXT: [[PTRA0:%.*]] = getelementptr float, ptr [[PTRA]], i32 0
; STOPAT2-NEXT: [[VECL:%.*]] = load <2 x float>, ptr [[PTRA0]], align 4
; STOPAT2-NEXT: store <2 x float> [[VECL]], ptr [[PTRA0]], align 4
; STOPAT2-NEXT: [[PTRB0:%.*]] = getelementptr float, ptr [[PTRB]], i32 0
; STOPAT2-NEXT: [[VECL1:%.*]] = load <2 x float>, ptr [[PTRB0]], align 4
; STOPAT2-NEXT: store <2 x float> [[VECL1]], ptr [[PTRB0]], align 4
; STOPAT2-NEXT: ret void
;
%ptrA0 = getelementptr float, ptr %ptrA, i32 0
%ptrA1 = getelementptr float, ptr %ptrA, i32 1
%ldA0 = load float, ptr %ptrA0
%ldA1 = load float, ptr %ptrA1
store float %ldA0, ptr %ptrA0
store float %ldA1, ptr %ptrA1

%ptrB0 = getelementptr float, ptr %ptrB, i32 0
%ptrB1 = getelementptr float, ptr %ptrB, i32 1
%ldB0 = load float, ptr %ptrB0
%ldB1 = load float, ptr %ptrB1
store float %ldB0, ptr %ptrB0
store float %ldB1, ptr %ptrB1

ret void
}