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gbaraldigbaraldi
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[LateLowerGC] Fix typo sret handling so we properly handle selects in the worklist (#57741)
Fixes #57737
1 parent ce747fe commit 96eb876

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3 files changed

+87
-6
lines changed

3 files changed

+87
-6
lines changed

‎src/llvm-gc-interface-passes.h‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -46,6 +46,7 @@
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#include "llvm-pass-helpers.h"
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#include <map>
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#include <string>
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#include <optional>
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#ifndef LLVM_GC_PASSES_H
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#define LLVM_GC_PASSES_H

‎src/llvm-late-gc-lowering.cpp‎

Lines changed: 16 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -1128,7 +1128,7 @@ void LateLowerGCFrame::FixUpRefinements(ArrayRef<int> PHINumbers, State &S)
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}
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// Look through instructions to find all possible allocas that might become the sret argument
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static SmallSetVector<AllocaInst *, 8> FindSretAllocas(Value* SRetArg) {
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static std::optional<SmallSetVector<AllocaInst *, 8>> FindSretAllocas(Value* SRetArg) {
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SmallSetVector<AllocaInst *, 8> allocas;
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if (AllocaInst *OneSRet = dyn_cast<AllocaInst>(SRetArg)) {
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allocas.insert(OneSRet); // Found it directly
@@ -1143,7 +1143,7 @@ static SmallSetVector<AllocaInst *, 8> FindSretAllocas(Value* SRetArg) {
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for (Value *Incoming : Phi->incoming_values()) {
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worklist.insert(Incoming);
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}
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} else if (SelectInst *SI = dyn_cast<SelectInst>(SRetArg)) {
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} else if (SelectInst *SI = dyn_cast<SelectInst>(V)) {
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auto TrueBranch = SI->getTrueValue();
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auto FalseBranch = SI->getFalseValue();
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if (TrueBranch && FalseBranch) {
@@ -1152,12 +1152,12 @@ static SmallSetVector<AllocaInst *, 8> FindSretAllocas(Value* SRetArg) {
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} else {
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llvm_dump(SI);
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dbgs() << "Malformed Select\n";
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abort();
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return {};
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}
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} else {
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llvm_dump(V);
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dbgs() << "Unexpected SRet argument\n";
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abort();
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return {};
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}
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}
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}
@@ -1221,10 +1221,15 @@ State LateLowerGCFrame::LocalScan(Function &F) {
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Type *ElT = getAttributeAtIndex(CI->getAttributes(), 1, Attribute::StructRet).getValueAsType();
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auto tracked = CountTrackedPointers(ElT, true);
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if (tracked.count) {
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SmallSetVector<AllocaInst *, 8> allocas = FindSretAllocas((CI->arg_begin()[0])->stripInBoundsOffsets());
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auto allocas_opt = FindSretAllocas((CI->arg_begin()[0])->stripInBoundsOffsets());
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// We know that with the right optimizations we can forward a sret directly from an argument
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// This hasn't been seen without adding IPO effects to julia functions but it's possible we need to handle that too
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// If they are tracked.all we can just pass through but if they have a roots bundle it's possible we need to emit some copies ¯\_(ツ)_/¯
1228+
if (!allocas_opt.has_value()) {
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llvm_dump(&F);
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abort();
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}
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auto allocas = allocas_opt.value();
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for (AllocaInst *SRet : allocas) {
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if (!(SRet->isStaticAlloca() && isa<PointerType>(ElT) && ElT->getPointerAddressSpace() == AddressSpace::Tracked)) {
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assert(!tracked.derived);
@@ -1233,7 +1238,12 @@ State LateLowerGCFrame::LocalScan(Function &F) {
12331238
}
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else {
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Value *arg1 = (CI->arg_begin()[1])->stripInBoundsOffsets();
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SmallSetVector<AllocaInst *, 8> gc_allocas = FindSretAllocas(arg1);
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auto gc_allocas_opt = FindSretAllocas(arg1);
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if (!gc_allocas_opt.has_value()) {
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llvm_dump(&F);
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abort();
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}
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auto gc_allocas = gc_allocas_opt.value();
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if (gc_allocas.size() == 0) {
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llvm_dump(CI);
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errs() << "Expected one Alloca at least\n";

‎test/llvmpasses/late-lower-gc-sret.ll‎

Lines changed: 70 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -79,3 +79,73 @@ ret: ; preds = %false, %true
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; CHECK: call void @julia.pop_gc_frame(ptr %gcframe)
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ret void
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}
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define hidden swiftcc void @sret_gc_root_phi_select(ptr nonnull swiftself %0, i1 %unpredictable, i1 %unpredictable2) {
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top:
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; CHECK-LABEL: @sret_gc_root_phi_select
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; CHECK: %gcframe = call ptr @julia.new_gc_frame(i32 3)
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; CHECK: call ptr @julia.get_gc_frame_slot(ptr %gcframe, i32 2)
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; CHECK: call ptr @julia.get_gc_frame_slot(ptr %gcframe, i32 1)
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; CHECK: call ptr @julia.get_gc_frame_slot(ptr %gcframe, i32 0)
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; CHECK: %pgcstack = call ptr @julia.get_pgcstack()
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; CHECK: call void @julia.push_gc_frame(ptr %gcframe, i32 3)
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; CHECK: alloca [3 x i64], align 8
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%pgcstack = call ptr @julia.get_pgcstack()
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%1 = alloca [3 x i64], align 8
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%2 = alloca ptr addrspace(10), align 8
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%3 = alloca ptr addrspace(10), align 8
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%4 = alloca ptr addrspace(10), align 8
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store i64 0, ptr %2, align 8
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store i64 0, ptr %3, align 8
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store i64 0, ptr %4, align 8
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br i1 %unpredictable, label %true, label %false
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true: ; preds = %top
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br label %ret
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false: ; preds = %top
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br label %ret
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ret: ; preds = %false, %true
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%5 = phi ptr [ %2, %true ], [ %3, %false ]
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%6 = select i1 %unpredictable2, ptr %4, ptr %5
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call swiftcc void @sret_call_gc(ptr noalias nocapture noundef sret({ ptr addrspace(10), i64, i64 }) %1, ptr noalias nocapture noundef %6, ptr nonnull swiftself %0)
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; CHECK: call void @julia.pop_gc_frame(ptr %gcframe)
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ret void
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}
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define hidden swiftcc void @sret_gc_root_select_phi(ptr nonnull swiftself %0, i1 %unpredictable, i1 %unpredictable2) {
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top:
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; CHECK-LABEL: @sret_gc_root_select_phi
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; CHECK: %gcframe = call ptr @julia.new_gc_frame(i32 3)
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; CHECK: call ptr @julia.get_gc_frame_slot(ptr %gcframe, i32 2)
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; CHECK: call ptr @julia.get_gc_frame_slot(ptr %gcframe, i32 1)
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; CHECK: call ptr @julia.get_gc_frame_slot(ptr %gcframe, i32 0)
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; CHECK: %pgcstack = call ptr @julia.get_pgcstack()
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; CHECK: call void @julia.push_gc_frame(ptr %gcframe, i32 3)
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; CHECK: alloca [3 x i64], align 8
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%pgcstack = call ptr @julia.get_pgcstack()
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%1 = alloca [3 x i64], align 8
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%2 = alloca ptr addrspace(10), align 8
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%3 = alloca ptr addrspace(10), align 8
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%4 = alloca ptr addrspace(10), align 8
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store i64 0, ptr %2, align 8
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store i64 0, ptr %3, align 8
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store i64 0, ptr %4, align 8
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%5 = select i1 %unpredictable2, ptr %3, ptr %4
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br i1 %unpredictable, label %true, label %false
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true: ; preds = %top
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br label %ret
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false: ; preds = %top
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br label %ret
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ret: ; preds = %false, %true
146+
%6 = phi ptr [ %2, %true ], [ %5, %false ]
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148+
call swiftcc void @sret_call_gc(ptr noalias nocapture noundef sret({ ptr addrspace(10), i64, i64 }) %1, ptr noalias nocapture noundef %6, ptr nonnull swiftself %0)
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; CHECK: call void @julia.pop_gc_frame(ptr %gcframe)
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ret void
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}

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