[lld] 064e990 - [lld][WebAssembly] Fix for --relocatable and signature mismatches

[Sam Clegg via llvm-commits]

Author: Sam Clegg
Date: 2020-05-13T10:27:09-07:00
New Revision: 064e9907ba069392427887405481d5e7abc1f662

URL: https://github.com/llvm/llvm-project/commit/064e9907ba069392427887405481d5e7abc1f662
DIFF: https://github.com/llvm/llvm-project/commit/064e9907ba069392427887405481d5e7abc1f662.diff

LOG: [lld][WebAssembly] Fix for --relocatable and signature mismatches

This is a followup to https://reviews.llvm.org/D78779.

When signatures mismatch we create set of variant symbols.  Some of
the fields in these symbols were not be initialized correct.
Specifically we were seeing isUsedInRegularObj not being set correctly,
leading to the symbol not getting included in the symbol table
and a crash writing relections in --reloctable mode.

There is larger refactor due here, but this is a minimal change the
fixes the bug at hand.

Differential Revision: https://reviews.llvm.org/D79756

Added: 
    lld/test/wasm/Inputs/sig_mismatch.s
    lld/test/wasm/signature-mismatch-relocatable.s

Modified: 
    lld/wasm/SymbolTable.cpp

Removed: 
    


################################################################################
diff  --git a/lld/test/wasm/Inputs/sig_mismatch.s b/lld/test/wasm/Inputs/sig_mismatch.s
new file mode 100644
index 000000000000..713186b9598f
--- /dev/null
+++ b/lld/test/wasm/Inputs/sig_mismatch.s
@@ -0,0 +1,12 @@
+.globl foo
+foo:
+   .functype foo (f32) -> (i32)
+   i32.const 0
+   end_function
+
+
+.globl call_foo
+call_foo:
+   .functype call_foo () -> (i32)
+   call foo
+   end_function

diff  --git a/lld/test/wasm/signature-mismatch-relocatable.s b/lld/test/wasm/signature-mismatch-relocatable.s
new file mode 100644
index 000000000000..7209995e01dc
--- /dev/null
+++ b/lld/test/wasm/signature-mismatch-relocatable.s
@@ -0,0 +1,57 @@
+# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown -o %t.o %s
+# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown -o %t2.o %S/Inputs/sig_mismatch.s
+# RUN: wasm-ld --relocatable %t.o %t2.o -o %t.wasm
+# RUN: obj2yaml %t.wasm | FileCheck %s
+
+# Regression test for handling of signature mismatches (variant function
+# symbols) and relocatable output.  This issue only occurred when the undefined
+# function was seen first and the defined function was referenced within the
+# the defining file (see %S/Inputs/sig_mismatch.s).
+
+.globl _start
+_start:
+  .functype _start () -> ()
+  i32.const 1
+  i64.const 2
+  i32.const 3
+  call foo
+  end_function
+
+.functype foo (i32, i64, i32) -> (i32)
+
+#      CHECK:  - Type:            CUSTOM
+# CHECK-NEXT:    Name:            linking
+# CHECK-NEXT:    Version:         2
+# CHECK-NEXT:    SymbolTable:
+# CHECK-NEXT:      - Index:           0
+# CHECK-NEXT:        Kind:            FUNCTION
+# CHECK-NEXT:        Name:            _start
+# CHECK-NEXT:        Flags:           [  ]
+# CHECK-NEXT:        Function:        1
+# CHECK-NEXT:      - Index:           1
+# CHECK-NEXT:        Kind:            FUNCTION
+# CHECK-NEXT:        Name:            foo
+# CHECK-NEXT:        Flags:           [  ]
+# CHECK-NEXT:        Function:        2
+# CHECK-NEXT:      - Index:           2
+# CHECK-NEXT:        Kind:            FUNCTION
+# CHECK-NEXT:        Name:            call_foo
+# CHECK-NEXT:        Flags:           [  ]
+# CHECK-NEXT:        Function:        3
+# CHECK-NEXT:      - Index:           3
+# CHECK-NEXT:        Kind:            FUNCTION
+# CHECK-NEXT:        Name:            'signature_mismatch:foo'
+# CHECK-NEXT:        Flags:           [ BINDING_LOCAL ]
+# CHECK-NEXT:        Function:        0
+# CHECK-NEXT:  - Type:            CUSTOM
+# CHECK-NEXT:    Name:            name
+# CHECK-NEXT:    FunctionNames:
+# CHECK-NEXT:      - Index:           0
+# CHECK-NEXT:        Name:            'signature_mismatch:foo'
+# CHECK-NEXT:      - Index:           1
+# CHECK-NEXT:        Name:            _start
+# CHECK-NEXT:      - Index:           2
+# CHECK-NEXT:        Name:            foo
+# CHECK-NEXT:      - Index:           3
+# CHECK-NEXT:        Name:            call_foo
+# CHECK-NEXT:...

diff  --git a/lld/wasm/SymbolTable.cpp b/lld/wasm/SymbolTable.cpp
index 6f6706e36aab..3933b7d96f73 100644
--- a/lld/wasm/SymbolTable.cpp
+++ b/lld/wasm/SymbolTable.cpp
@@ -113,6 +113,7 @@ std::pair<Symbol *, bool> SymbolTable::insertName(StringRef name) {
   sym->isUsedInRegularObj = false;
   sym->canInline = true;
   sym->traced = trace;
+  sym->forceExport = false;
   symVector.emplace_back(sym);
   return {sym, true};
 }
@@ -598,6 +599,11 @@ bool SymbolTable::getFunctionVariant(Symbol* sym, const WasmSignature *sig,
     // Create a new variant;
     LLVM_DEBUG(dbgs() << "added new variant\n");
     variant = reinterpret_cast<Symbol *>(make<SymbolUnion>());
+    variant->isUsedInRegularObj =
+        !file || file->kind() == InputFile::ObjectKind;
+    variant->canInline = true;
+    variant->traced = false;
+    variant->forceExport = false;
     variants.push_back(variant);
   } else {
     LLVM_DEBUG(dbgs() << "variant already exists: " << toString(*variant) << "\n");