[WebAssembly] Store section alignment as a power of 2

[sbc100]

Summary

This change bumps for version number of the wasm object file
metadata.

See https://github.com/WebAssembly/tool-conventions/pull/92

[msearles]

lld/trunk/wasm/OutputSegment.h

29 ↗

(On Diff #181953)

Looks like one of our internal windows builders is failing due to this change:

c:\buildagent\work\7a156dd62df26211\opencl\drivers\opencl\compiler\llvm\tools\lld\wasm\OutputSegment.h(29): error C2220: warning treated as error - no 'object' file generated
[00:38:36][Step 2/4]

c:\buildagent\work\7a156dd62df26211\opencl\drivers\opencl\compiler\llvm\tools\lld\wasm\OutputSegment.h(29): warning C4334: '<<': result of 32-bit shift implicitly converted to 64 bits (was 64-bit shift intended?)

Perhaps it should be 1ULL , not 1 ?
Trying to get onto our windows builder to test this.
Thanks.

[sbc100]

Yes, it looks like ULL should fix the warning: https://reviews.llvm.org/D56874

[msearles]

In D56762#1362101, @sbc100 wrote:

Yes, it looks like ULL should fix the warning: https://reviews.llvm.org/D56874

One more:

lld/trunk/wasm/Writer.cpp:694
MemoryPtr = alignTo(MemoryPtr, 1 << Seg->Alignment);

1 -> 1ULL

test/wasm/Inputs/globals.yaml

Functions:
         Locals:
         Body:            2381808080000B
     Relocations:
       - Type:            R_WEBASSEMBLY_GLOBAL_INDEX_LEB
         Index:           1
         Offset:          0x00000004
   - Type:            CUSTOM
     Name:            linking
-    Version:         1
+    Version:         2
     SymbolTable:
       - Index:           0
         Kind:            GLOBAL
         Name:            unused_global
         Flags:           [ VISIBILITY_HIDDEN ]
         Global:          0
       - Index:           1
         Kind:            GLOBAL

test/wasm/Inputs/undefined-globals.yaml

Functions:
         Locals:
         Body:            2381808080000B
     Relocations:
       - Type:            R_WEBASSEMBLY_GLOBAL_INDEX_LEB
         Index:           1
         Offset:          0x00000004
   - Type:            CUSTOM
     Name:            linking
-    Version:         1
+    Version:         2
     SymbolTable:
       - Index:           0
         Kind:            GLOBAL
         Name:            unused_undef_global
         Flags:           [ VISIBILITY_HIDDEN, UNDEFINED ]
         Global:          0
       - Index:           1
         Kind:            GLOBAL

test/wasm/locals-duplicate.test

 ; RELOC-NEXT:       - SectionOffset:   32
 ; RELOC-NEXT:         MemoryIndex:     0
 ; RELOC-NEXT:         Offset:
 ; RELOC-NEXT:           Opcode:          I32_CONST
 ; RELOC-NEXT:           Value:           16
 ; RELOC-NEXT:         Content:         '0000000000000000'
 ; RELOC-NEXT:   - Type:            CUSTOM
 ; RELOC-NEXT:     Name:            linking
-; RELOC-NEXT:     Version:         1
+; RELOC-NEXT:     Version:         2
 ; RELOC-NEXT:     SymbolTable:
 ; RELOC-NEXT:       - Index:           0
 ; RELOC-NEXT:         Kind:            FUNCTION
 ; RELOC-NEXT:         Name:            colliding_func1
 ; RELOC-NEXT:         Flags:           [ BINDING_LOCAL ]
 ; RELOC-NEXT:         Function:        0
 ; RELOC-NEXT:       - Index:           1
 ; RELOC-NEXT:         Kind:            FUNCTION

 ; RELOC-NEXT:       - Index:           23
 ; RELOC-NEXT:         Kind:            FUNCTION
 ; RELOC-NEXT:         Name:            get_func3B
 ; RELOC-NEXT:         Flags:           [  ]
 ; RELOC-NEXT:         Function:        17
 ; RELOC-NEXT:     SegmentInfo:
 ; RELOC-NEXT:       - Index:           0
 ; RELOC-NEXT:         Name:            .bss.colliding_global1
-; RELOC-NEXT:         Alignment:       4
+; RELOC-NEXT:         Alignment:       2
 ; RELOC-NEXT:         Flags:           [  ]
 ; RELOC-NEXT:       - Index:           1
 ; RELOC-NEXT:         Name:            .bss.colliding_global2
-; RELOC-NEXT:         Alignment:       4
+; RELOC-NEXT:         Alignment:       2
 ; RELOC-NEXT:         Flags:           [  ]
 ; RELOC-NEXT:       - Index:           2
 ; RELOC-NEXT:         Name:            .bss.colliding_global3
-; RELOC-NEXT:         Alignment:       4
+; RELOC-NEXT:         Alignment:       2
 ; RELOC-NEXT:         Flags:           [  ]
 ; RELOC-NEXT:   - Type:            CUSTOM
 ; RELOC-NEXT:     Name:            name
 ; RELOC-NEXT:     FunctionNames:
 ; RELOC-NEXT:       - Index:           0
 ; RELOC-NEXT:         Name:            colliding_func1
 ; RELOC-NEXT:       - Index:           1
 ; RELOC-NEXT:         Name:            colliding_func2

test/wasm/many-functions.ll

 ; CHECK-NEXT:       - SectionOffset:   15
 ; CHECK-NEXT:         MemoryIndex:     0
 ; CHECK-NEXT:         Offset:
 ; CHECK-NEXT:           Opcode:          I32_CONST
 ; CHECK-NEXT:           Value:           4
 ; CHECK-NEXT:         Content:         '01000000'
 ; CHECK-NEXT:   - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            linking
-; CHECK-NEXT:     Version:         1
+; CHECK-NEXT:     Version:         2
 ; CHECK-NEXT:     SymbolTable:
 ; CHECK-NEXT:       - Index:           0
 ; CHECK-NEXT:         Kind:            FUNCTION
 ; CHECK-NEXT:         Name:            f1
 ; CHECK-NEXT:         Flags:           [  ]
 ; CHECK-NEXT:         Function:        0
 ; CHECK-NEXT:       - Index:           1
 ; CHECK-NEXT:         Kind:            DATA

 ; CHECK-NEXT:       - Index:           131
 ; CHECK-NEXT:         Kind:            FUNCTION
 ; CHECK-NEXT:         Name:            func
 ; CHECK-NEXT:         Flags:           [  ]
 ; CHECK-NEXT:         Function:        129
 ; CHECK-NEXT:     SegmentInfo:
 ; CHECK-NEXT:       - Index:           0
 ; CHECK-NEXT:         Name:            .data.g0
-; CHECK-NEXT:         Alignment:       4
+; CHECK-NEXT:         Alignment:       2
 ; CHECK-NEXT:         Flags:           [ ]
 ; CHECK-NEXT:       - Index:           1
 ; CHECK-NEXT:         Name:            .data.foo
-; CHECK-NEXT:         Alignment:       4
+; CHECK-NEXT:         Alignment:       2
 ; CHECK-NEXT:         Flags:           [ ]

test/wasm/relocatable.ll

 ; CHECK-NEXT:       - SectionOffset:   54
 ; CHECK-NEXT:         MemoryIndex:     0
 ; CHECK-NEXT:         Offset:
 ; CHECK-NEXT:           Opcode:          I32_CONST
 ; CHECK-NEXT:           Value:           28
 ; CHECK-NEXT:         Content:         '616263'
 ; CHECK-NEXT:   - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            linking
-; CHECK-NEXT:     Version:         1
+; CHECK-NEXT:     Version:         2
 ; CHECK-NEXT:     SymbolTable:
 ; CHECK-NEXT:       - Index:           0
 ; CHECK-NEXT:         Kind:            FUNCTION
 ; CHECK-NEXT:         Name:            hello
 ; CHECK-NEXT:         Flags:           [ VISIBILITY_HIDDEN ]
 ; CHECK-NEXT:         Function:        3
 ; CHECK-NEXT:       - Index:           1
 ; CHECK-NEXT:         Kind:            DATA

 ; CHECK-NEXT:         Size:            4
 ; CHECK-NEXT:       - Index:           12
 ; CHECK-NEXT:         Kind:            DATA
 ; CHECK-NEXT:         Name:            data_import
 ; CHECK-NEXT:         Flags:           [ UNDEFINED ]
 ; CHECK-NEXT:     SegmentInfo:
 ; CHECK-NEXT:       - Index:           0
 ; CHECK-NEXT:         Name:            .rodata.hello_str
-; CHECK-NEXT:         Alignment:       1
+; CHECK-NEXT:         Alignment:       0
 ; CHECK-NEXT:         Flags:           [  ]
 ; CHECK-NEXT:       - Index:           1
 ; CHECK-NEXT:         Name:            .data.func_addr1
-; CHECK-NEXT:         Alignment:       4
+; CHECK-NEXT:         Alignment:       2
 ; CHECK-NEXT:         Flags:           [  ]
 ; CHECK-NEXT:       - Index:           2
 ; CHECK-NEXT:         Name:            .data.func_addr2
-; CHECK-NEXT:         Alignment:       4
+; CHECK-NEXT:         Alignment:       2
 ; CHECK-NEXT:         Flags:           [  ]
 ; CHECK-NEXT:       - Index:           3
 ; CHECK-NEXT:         Name:            .data.func_addr3
-; CHECK-NEXT:         Alignment:       4
+; CHECK-NEXT:         Alignment:       2
 ; CHECK-NEXT:         Flags:           [  ]
 ; CHECK-NEXT:       - Index:           4
 ; CHECK-NEXT:         Name:            .data.data_addr1
-; CHECK-NEXT:         Alignment:       8
+; CHECK-NEXT:         Alignment:       3
 ; CHECK-NEXT:         Flags:           [  ]
 ; CHECK-NEXT:       - Index:           5
 ; CHECK-NEXT:         Name:            .rodata.data_comdat
-; CHECK-NEXT:         Alignment:       1
+; CHECK-NEXT:         Alignment:       0
 ; CHECK-NEXT:         Flags:           [  ]
 ; CHECK-NEXT:     Comdats:
 ; CHECK-NEXT:       - Name:            func_comdat
 ; CHECK-NEXT:         Entries:
 ; CHECK-NEXT:           - Kind:            FUNCTION
 ; CHECK-NEXT:             Index:           5
 ; CHECK-NEXT:           - Kind:            DATA
 ; CHECK-NEXT:             Index:           5

test/wasm/stack-pointer.ll

 ; CHECK-NEXT:         Index:           1
 ; CHECK-NEXT:         Offset:          0x00000004
 ; CHECK-NEXT:     Functions:
 ; CHECK-NEXT:       - Index:           0
 ; CHECK-NEXT:         Locals:
 ; CHECK-NEXT:         Body:            23808080800041106B1A41000B
 ; CHECK-NEXT:   - Type:            CUSTOM
 ; CHECK-NEXT:     Name:            linking
-; CHECK-NEXT:     Version:         1
+; 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:        0
 ; CHECK-NEXT:       - Index:           1
 ; CHECK-NEXT:         Kind:            GLOBAL

test/wasm/weak-alias.ll

 ; RELOC-NEXT:         Body:            23808080800041106B220024808080800020004181808080003602081081808080002101200041106A24808080800020010B
 ; RELOC-NEXT:       - Index:           5
 ; RELOC-NEXT:         Locals:
 ; RELOC-NEXT:           - Type:            I32
 ; RELOC-NEXT:             Count:           2
 ; RELOC-NEXT:         Body:            23808080800041106B220024808080800020004181808080003602081081808080002101200041106A24808080800020010B
 ; RELOC-NEXT:   - Type:            CUSTOM
 ; RELOC-NEXT:     Name:            linking
-; RELOC-NEXT:     Version:         1
+; RELOC-NEXT:     Version:         2
 ; RELOC-NEXT:     SymbolTable:
 ; RELOC-NEXT:       - Index:           0
 ; RELOC-NEXT:         Kind:            FUNCTION
 ; RELOC-NEXT:         Name:            _start
 ; RELOC-NEXT:         Flags:           [  ]
 ; RELOC-NEXT:         Function:        0
 ; RELOC-NEXT:       - Index:           1
 ; RELOC-NEXT:         Kind:            FUNCTION

wasm/OutputSegment.h

 
 class OutputSegment {
 public:
   OutputSegment(StringRef N, uint32_t Index) : Name(N), Index(Index) {}
 
   void addInputSegment(InputSegment *InSeg) {
     Alignment = std::max(Alignment, InSeg->getAlignment());
     InputSegments.push_back(InSeg);
-    Size = llvm::alignTo(Size, InSeg->getAlignment());
+    Size = llvm::alignTo(Size, 1 << InSeg->getAlignment());
     InSeg->OutputSeg = this;
     InSeg->OutputSegmentOffset = Size;
     Size += InSeg->getSize();
   }
 
   StringRef Name;
   const uint32_t Index;
   uint32_t SectionOffset = 0;

wasm/Writer.cpp

 // linker.
 // See
 // https://github.com/WebAssembly/tool-conventions/blob/master/DynamicLinking.md
 void Writer::createDylinkSection() {
   SyntheticSection *Section = createSyntheticSection(WASM_SEC_CUSTOM, "dylink");
   raw_ostream &OS = Section->getStream();
 
   writeUleb128(OS, MemSize, "MemSize");
-  writeUleb128(OS, int(log2(MemAlign)), "MemAlign");
+  writeUleb128(OS, MemAlign, "MemAlign");
   writeUleb128(OS, IndirectFunctions.size(), "TableSize");
   writeUleb128(OS, 0, "TableAlign");
   writeUleb128(OS, 0, "Needed");  // TODO: Support "needed" shared libraries
 }
 
 // Create the custom "linking" section containing linker metadata.
 // This is only created when relocatable output is requested.
 void Writer::createLinkingSection() {
void Writer::layoutMemory() {
   // Arbitrarily set __dso_handle handle to point to the start of the data
   // segments.
   if (WasmSym::DsoHandle)
     WasmSym::DsoHandle->setVirtualAddress(DataStart);
 
   MemAlign = 0;
   for (OutputSegment *Seg : Segments) {
     MemAlign = std::max(MemAlign, Seg->Alignment);
-    MemoryPtr = alignTo(MemoryPtr, Seg->Alignment);
+    MemoryPtr = alignTo(MemoryPtr, 1 << Seg->Alignment);
     Seg->StartVA = MemoryPtr;
     log(formatv("mem: {0,-15} offset={1,-8} size={2,-8} align={3}", Seg->Name,
                 MemoryPtr, Seg->Size, Seg->Alignment));
     MemoryPtr += Seg->Size;
   }
 
   // TODO: Add .bss space here.
   if (WasmSym::DataEnd)