From 9fd0567fb5d2ffbf217e3417f77dce479509f92e Mon Sep 17 00:00:00 2001
From: Ayke van Laethem <aykevanlaethem@gmail.com>
Date: Thu, 22 Dec 2022 00:48:12 +0000
Subject: [PATCH] compiler: fix stack overflow when creating recursive pointer
 types

There were two types that could result in a compiler stack overflow.
This is difficult to fix in LLVM 14, so I won't even bother. However,
this is trivial to fix with opaque pointers in LLVM 15. Therefore, this
fix is for LLVM 15 only.

Fixes: https://github.com/tinygo-org/tinygo/issues/3341
---
 compiler/channel.go        |  4 ++--
 compiler/compiler.go       | 16 ++++++++++++----
 compiler/testdata/basic.go |  6 ++++++
 compiler/testdata/basic.ll |  2 ++
 4 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/compiler/channel.go b/compiler/channel.go
index 81f84565..0ce9aa66 100644
--- a/compiler/channel.go
+++ b/compiler/channel.go
@@ -43,7 +43,7 @@ func (b *builder) createChanSend(instr *ssa.Send) {
 	}
 
 	// Allocate blockedlist buffer.
-	channelBlockedList := b.mod.GetTypeByName("runtime.channelBlockedList")
+	channelBlockedList := b.getLLVMRuntimeType("channelBlockedList")
 	channelBlockedListAlloca, channelBlockedListAllocaCast, channelBlockedListAllocaSize := b.createTemporaryAlloca(channelBlockedList, "chan.blockedList")
 
 	// Do the send.
@@ -75,7 +75,7 @@ func (b *builder) createChanRecv(unop *ssa.UnOp) llvm.Value {
 	}
 
 	// Allocate blockedlist buffer.
-	channelBlockedList := b.mod.GetTypeByName("runtime.channelBlockedList")
+	channelBlockedList := b.getLLVMRuntimeType("channelBlockedList")
 	channelBlockedListAlloca, channelBlockedListAllocaCast, channelBlockedListAllocaSize := b.createTemporaryAlloca(channelBlockedList, "chan.blockedList")
 
 	// Do the receive.
diff --git a/compiler/compiler.go b/compiler/compiler.go
index 8b6e8661..903031fb 100644
--- a/compiler/compiler.go
+++ b/compiler/compiler.go
@@ -76,6 +76,7 @@ type compilerContext struct {
 	i8ptrType        llvm.Type // for convenience
 	rawVoidFuncType  llvm.Type // for convenience
 	funcPtrAddrSpace int
+	hasTypedPointers bool // for LLVM 14 backwards compatibility
 	uintptrType      llvm.Type
 	program          *ssa.Program
 	diagnostics      []error
@@ -123,6 +124,7 @@ func newCompilerContext(moduleName string, machine llvm.TargetMachine, config *C
 	dummyFuncType := llvm.FunctionType(c.ctx.VoidType(), nil, false)
 	dummyFunc := llvm.AddFunction(c.mod, "tinygo.dummy", dummyFuncType)
 	c.funcPtrAddrSpace = dummyFunc.Type().PointerAddressSpace()
+	c.hasTypedPointers = c.i8ptrType != llvm.PointerType(c.ctx.Int16Type(), 0) // with opaque pointers, all pointers are the same type (LLVM 15+)
 	c.rawVoidFuncType = dummyFunc.Type()
 	dummyFunc.EraseFromParentAsFunction()
 
@@ -422,14 +424,20 @@ func (c *compilerContext) makeLLVMType(goType types.Type) llvm.Type {
 		}
 		return c.getLLVMType(typ.Underlying())
 	case *types.Pointer:
-		ptrTo := c.getLLVMType(typ.Elem())
-		return llvm.PointerType(ptrTo, 0)
+		if c.hasTypedPointers {
+			ptrTo := c.getLLVMType(typ.Elem())
+			return llvm.PointerType(ptrTo, 0)
+		}
+		return c.i8ptrType // all pointers are the same
 	case *types.Signature: // function value
 		return c.getFuncType(typ)
 	case *types.Slice:
-		elemType := c.getLLVMType(typ.Elem())
+		ptrType := c.i8ptrType
+		if c.hasTypedPointers {
+			ptrType = llvm.PointerType(c.getLLVMType(typ.Elem()), 0)
+		}
 		members := []llvm.Type{
-			llvm.PointerType(elemType, 0),
+			ptrType,
 			c.uintptrType, // len
 			c.uintptrType, // cap
 		}
diff --git a/compiler/testdata/basic.go b/compiler/testdata/basic.go
index d2b4a96d..6c6f983e 100644
--- a/compiler/testdata/basic.go
+++ b/compiler/testdata/basic.go
@@ -90,3 +90,9 @@ func foo() {
 	// Use this type.
 	func(b kv) {}(kv{})
 }
+
+type T1 []T1
+type T2 [2]*T2
+
+var a T1
+var b T2
diff --git a/compiler/testdata/basic.ll b/compiler/testdata/basic.ll
index 6ef0dc92..4daf7b7c 100644
--- a/compiler/testdata/basic.ll
+++ b/compiler/testdata/basic.ll
@@ -7,6 +7,8 @@ target triple = "wasm32-unknown-wasi"
 %main.kv.0 = type { i8, i32, i32, i32 }
 
 @main.kvGlobal = hidden global %main.kv zeroinitializer, align 4
+@main.a = hidden global { ptr, i32, i32 } zeroinitializer, align 4
+@main.b = hidden global [2 x ptr] zeroinitializer, align 4
 
 declare noalias nonnull ptr @runtime.alloc(i32, ptr, ptr) #0