[lld][Alignment][NFC] Use Align instead of log2 of alignment in Wasm Sections

I intend to slowly upgrade all alignments to the Align type in lld as well.
Some places talk about alignment in Bytes while other specify them as Log2(Bytes).
Let's make sure all of this is coherent.

Differential Revision: https://reviews.llvm.org/D139181

Author: gchatelet

lld/wasm/InputChunks.h

@@ -85,7 +85,7 @@ class InputChunk {
   OutputSection *outputSec = nullptr;
   uint32_t comdat = UINT32_MAX;
   uint32_t inputSectionOffset = 0;
-  uint32_t alignment;
+  llvm::Align alignment;
   uint32_t flags;
 
   // Only applies to data segments.
@@ -109,8 +109,8 @@ class InputChunk {
 protected:
   InputChunk(ObjFile *f, Kind k, StringRef name, uint32_t alignment = 0,
              uint32_t flags = 0)
-      : name(name), file(f), alignment(alignment), flags(flags), sectionKind(k),
-        live(!config->gcSections), discarded(false) {}
+      : name(name), file(f), alignment(1ULL << alignment), flags(flags),
+        sectionKind(k), live(!config->gcSections), discarded(false) {}
   ArrayRef<uint8_t> data() const { return rawData; }
   uint64_t getTombstone() const;
 

lld/wasm/OutputSegment.cpp

@@ -22,10 +22,10 @@ namespace wasm {
 void OutputSegment::addInputSegment(InputChunk *inSeg) {
   alignment = std::max(alignment, inSeg->alignment);
   inputSegments.push_back(inSeg);
-  size = llvm::alignTo(size, 1ULL << inSeg->alignment);
+  size = llvm::alignTo(size, inSeg->alignment);
   LLVM_DEBUG(dbgs() << "addInputSegment: " << inSeg->name << " oname=" << name
-                    << " size=" << inSeg->getSize()
-                    << " align=" << inSeg->alignment << " at:" << size << "\n");
+                    << " size=" << inSeg->getSize() << " align="
+                    << Log2(inSeg->alignment) << " at:" << size << "\n");
   inSeg->outputSeg = this;
   inSeg->outputSegmentOffset = size;
   size += inSeg->getSize();
@@ -56,8 +56,9 @@ void OutputSegment::finalizeInputSegments() {
     });
     if (i == mergedSegments.end()) {
       LLVM_DEBUG(llvm::dbgs() << "new merge segment: " << name
-                              << " alignment=" << ms->alignment << "\n");
-      auto *syn = make<SyntheticMergedChunk>(name, ms->alignment, ms->flags);
+                              << " alignment=" << Log2(ms->alignment) << "\n");
+      auto *syn =
+          make<SyntheticMergedChunk>(name, Log2(ms->alignment), ms->flags);
       syn->outputSeg = this;
       mergedSegments.push_back(syn);
       i = std::prev(mergedSegments.end());
@@ -74,7 +75,7 @@ void OutputSegment::finalizeInputSegments() {
   inputSegments = newSegments;
   size = 0;
   for (InputChunk *seg : inputSegments) {
-    size = llvm::alignTo(size, 1ULL << seg->alignment);
+    size = llvm::alignTo(size, seg->alignment);
     LLVM_DEBUG(llvm::dbgs() << "outputSegmentOffset set: " << seg->name
                             << " -> " << size << "\n");
     seg->outputSegmentOffset = size;

lld/wasm/OutputSegment.h

@@ -38,7 +38,7 @@ class OutputSegment {
   uint32_t linkingFlags = 0;
   uint32_t initFlags = 0;
   uint32_t sectionOffset = 0;
-  uint32_t alignment = 0;
+  llvm::Align alignment;
   uint64_t startVA = 0;
   std::vector<InputChunk *> inputSegments;
 

lld/wasm/SyntheticSections.cpp

@@ -668,7 +668,7 @@ void LinkingSection::writeBody() {
     writeUleb128(sub.os, dataSegments.size(), "num data segments");
     for (const OutputSegment *s : dataSegments) {
       writeStr(sub.os, s->name, "segment name");
-      writeUleb128(sub.os, s->alignment, "alignment");
+      writeUleb128(sub.os, Log2(s->alignment), "alignment");
       writeUleb128(sub.os, s->linkingFlags, "flags");
     }
     sub.writeTo(os);

lld/wasm/Writer.cpp

@@ -288,11 +288,12 @@ void Writer::layoutMemory() {
 
   out.dylinkSec->memAlign = 0;
   for (OutputSegment *seg : segments) {
-    out.dylinkSec->memAlign = std::max(out.dylinkSec->memAlign, seg->alignment);
-    memoryPtr = alignTo(memoryPtr, 1ULL << seg->alignment);
+    out.dylinkSec->memAlign =
+        std::max(out.dylinkSec->memAlign, Log2(seg->alignment));
+    memoryPtr = alignTo(memoryPtr, 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, Log2(seg->alignment)));
 
     if (!config->relocatable && seg->isTLS()) {
       if (WasmSym::tlsSize) {
@@ -301,7 +302,7 @@ void Writer::layoutMemory() {
       }
       if (WasmSym::tlsAlign) {
         auto *tlsAlign = cast<DefinedGlobal>(WasmSym::tlsAlign);
-        setGlobalPtr(tlsAlign, int64_t{1} << seg->alignment);
+        setGlobalPtr(tlsAlign, seg->alignment.value());
       }
       if (!config->sharedMemory && WasmSym::tlsBase) {
         auto *tlsBase = cast<DefinedGlobal>(WasmSym::tlsBase);