[PATCH] D115161: [IR] Allow the 'align' param attr on vectors of pointers

[Fraser Cormack via Phabricator via llvm-commits]

frasercrmck created this revision.
frasercrmck added reviewers: simoll, craig.topper, anna, fhahn, jdoerfert, dantrushin.
Herald added subscribers: dexonsmith, rogfer01, hiraditya.
frasercrmck requested review of this revision.
Herald added subscribers: llvm-commits, vkmr.
Herald added a project: LLVM.

This patch extends the available uses of the 'align' parameter attribute
to include vectors of pointers. The attribute specifies pointer
alignment element-wise.

This change was previously requested and discussed in D87304 <https://reviews.llvm.org/D87304>.

The vector predication (VP) intrinsics intend to use this for scatter
and gather operations, as they lack the explicit alignment parameter
that the masked versions use.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D115161

Files:
  llvm/docs/LangRef.rst
  llvm/lib/IR/Attributes.cpp
  llvm/test/Bitcode/attributes.ll


Index: llvm/test/Bitcode/attributes.ll
===================================================================
--- llvm/test/Bitcode/attributes.ll
+++ llvm/test/Bitcode/attributes.ll
@@ -478,6 +478,11 @@
         ret void;
 }
 
+define void @f81(<4 x i8*> align 32 %0, <vscale x 1 x double*> align 64 %1) {
+; CHECK: define void @f81(<4 x i8*> align 32 %0, <vscale x 1 x double*> align 64 %1)
+  ret void
+}
+
 ; CHECK: attributes #0 = { noreturn }
 ; CHECK: attributes #1 = { nounwind }
 ; CHECK: attributes #2 = { readnone }
Index: llvm/lib/IR/Attributes.cpp
===================================================================
--- llvm/lib/IR/Attributes.cpp
+++ llvm/lib/IR/Attributes.cpp
@@ -1812,12 +1812,12 @@
   AttrBuilder Incompatible;
 
   if (!Ty->isIntegerTy())
-    // Attribute that only apply to integers.
+    // Attributes that only apply to integers.
     Incompatible.addAttribute(Attribute::SExt)
       .addAttribute(Attribute::ZExt);
 
   if (!Ty->isPointerTy())
-    // Attribute that only apply to pointers.
+    // Attributes that only apply to pointers.
     Incompatible.addAttribute(Attribute::Nest)
         .addAttribute(Attribute::NoAlias)
         .addAttribute(Attribute::NoCapture)
@@ -1825,7 +1825,6 @@
         .addAttribute(Attribute::ReadNone)
         .addAttribute(Attribute::ReadOnly)
         .addAttribute(Attribute::SwiftError)
-        .addAlignmentAttr(1)             // the int here is ignored
         .addDereferenceableAttr(1)       // the int here is ignored
         .addDereferenceableOrNullAttr(1) // the int here is ignored
         .addPreallocatedAttr(Ty)
@@ -1835,6 +1834,10 @@
         .addByRefAttr(Ty)
         .addTypeAttr(Attribute::ElementType, Ty);
 
+  if (!Ty->isPtrOrPtrVectorTy())
+    // Attributes that only apply to pointers or vectors of pointers.
+    Incompatible.addAlignmentAttr(1); // the int here is ignored
+
   // Some attributes can apply to all "values" but there are no `void` values.
   if (Ty->isVoidTy())
     Incompatible.addAttribute(Attribute::NoUndef);
Index: llvm/docs/LangRef.rst
===================================================================
--- llvm/docs/LangRef.rst
+++ llvm/docs/LangRef.rst
@@ -1210,12 +1210,14 @@
 .. _attr_align:
 
 ``align <n>`` or ``align(<n>)``
-    This indicates that the pointer value has the specified alignment.
-    If the pointer value does not have the specified alignment,
-    :ref:`poison value <poisonvalues>` is returned or passed instead. The
-    ``align`` attribute should be combined with the ``noundef`` attribute to
-    ensure a pointer is aligned, or otherwise the behavior is undefined. Note
-    that ``align 1`` has no effect on non-byval, non-preallocated arguments.
+    This indicates that the pointer value or vector of pointers has the
+    specified alignment. If applied to a vector of pointers, *all* pointers
+    (elements) have the specified alignment. If the pointer value does not have
+    the specified alignment, :ref:`poison value <poisonvalues>` is returned or
+    passed instead.  The ``align`` attribute should be combined with the
+    ``noundef`` attribute to ensure a pointer is aligned, or otherwise the
+    behavior is undefined. Note that ``align 1`` has no effect on non-byval,
+    non-preallocated arguments.
 
     Note that this attribute has additional semantics when combined with the
     ``byval`` or ``preallocated`` attribute, which are documented there.


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