[llvm] [WebAssembly] Add path to PIC mode for wasm tables (PR #67545)

[Paulo Matos via llvm-commits]

https://github.com/pmatos created https://github.com/llvm/llvm-project/pull/67545

Currently tables cannot be shared between compilation units, therefore
no special treatment is needed for tables.

Fixes #65191

>From 6dc3864d925bc878ae28efaf508ff5dc7ae07147 Mon Sep 17 00:00:00 2001
From: Paulo Matos <pmatos at igalia.com>
Date: Wed, 27 Sep 2023 13:50:39 +0200
Subject: [PATCH] [WebAssembly] Add path to PIC mode for wasm tables

Currently tables cannot be shared between compilation units, therefore
no special treatment is needed for tables.

Fixes #65191
---
 .../Target/WebAssembly/WebAssemblyISelLowering.cpp   | 10 ++++++++--
 llvm/test/MC/WebAssembly/reloc-pic.s                 | 12 ++++++++++--
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
index fd154a90edef1d9..b67615d82d04a54 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
@@ -1724,8 +1724,14 @@ SDValue WebAssemblyTargetLowering::LowerGlobalAddress(SDValue Op,
     fail(DL, DAG, "Invalid address space for WebAssembly target");
 
   unsigned OperandFlags = 0;
-  if (isPositionIndependent()) {
-    const GlobalValue *GV = GA->getGlobal();
+  const GlobalValue *GV = GA->getGlobal();
+  // is PIC but not a WebAssembly table.
+  // Since WebAssembly tables cannot yet be shared accross modules, we don't need special
+  // treatment for tables in PIC mode.
+  if (isPositionIndependent() && 
+      !(GV->getValueType()->isArrayTy() && 
+        WebAssembly::isWebAssemblyReferenceType(GV->getValueType()->getArrayElementType()))) {
+    
     if (getTargetMachine().shouldAssumeDSOLocal(*GV->getParent(), GV)) {
       MachineFunction &MF = DAG.getMachineFunction();
       MVT PtrVT = getPointerTy(MF.getDataLayout());
diff --git a/llvm/test/MC/WebAssembly/reloc-pic.s b/llvm/test/MC/WebAssembly/reloc-pic.s
index dd5d315cc2ce03f..1758820da93479a 100644
--- a/llvm/test/MC/WebAssembly/reloc-pic.s
+++ b/llvm/test/MC/WebAssembly/reloc-pic.s
@@ -1,5 +1,5 @@
-# RUN: llvm-mc -triple=wasm32-unknown-unknown -filetype=obj < %s | obj2yaml | FileCheck %s
-# RUN: llvm-mc -triple=wasm32-unknown-unknown -mattr=+reference-types -filetype=obj < %s | obj2yaml | FileCheck --check-prefix=REF %s
+# RUN: sed -e '/^REF-/d' %s | llvm-mc -triple=wasm32-unknown-unknown -filetype=obj | obj2yaml | FileCheck %s
+# RUN: sed -e 's/^REF-//g' %s | llvm-mc -triple=wasm32-unknown-unknown -mattr=+reference-types -filetype=obj | obj2yaml | FileCheck --check-prefix=REF %s
 
 # Verify that @GOT relocation entryes result in R_WASM_GLOBAL_INDEX_LEB against
 # against the corrsponding function or data symbol and that the corresponding
@@ -50,6 +50,9 @@ hidden_func:
 #.hidden hidden_data
 .size default_data, 4
 
+REF-mytable:
+REF-.tabletype mytable, externref
+
 # CHECK:      --- !WASM
 # CHECK-NEXT: FileHeader:
 # CHECK-NEXT:   Version:         0x1
@@ -209,6 +212,11 @@ hidden_func:
 # CHECK-NEXT:         Function:        5
 # REF:              - Index:           10
 # REF-NEXT:           Kind:            TABLE
+# REF-NEXT:           Name:            mytable
+# REF-NEXT:           Flags:           [ UNDEFINED ]
+# REF-NEXT:           Table:           1
+# REF-NEXT:         - Index:           11
+# REF-NEXT:           Kind:            TABLE
 # REF-NEXT:           Name:            __indirect_function_table
 # REF-NEXT:           Flags:           [ UNDEFINED, NO_STRIP ]
 # REF-NEXT:           Table:           0