[PATCH] D122130: Verify parameter alignment attribute

[LuoYuanke via Phabricator via llvm-commits]

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In DAGISel, the parameter alignment only have 4 bits to hold the value.
The encode(alignment) would plus the value by 1, so the max aligment that
ISel can support is 2^14. This patch verify align attribute for parameter.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D122130

Files:
  llvm/lib/IR/Verifier.cpp
  llvm/test/Verifier/param-attr-align.ll


Index: llvm/test/Verifier/param-attr-align.ll
===================================================================
--- /dev/null
+++ llvm/test/Verifier/param-attr-align.ll
@@ -0,0 +1,11 @@
+; RUN: not llvm-as < %s 2>&1 | FileCheck %s
+
+; CHECK: Attribute 'align 32768' exceed the max size 2^14
+define dso_local void @foo(i8* %p) {
+entry:
+  %p1 = bitcast i8* %p to <8 x float>*
+  call void @bar(<8 x float>* noundef byval(<8 x float>) align 32768 %p1)
+  ret void
+}
+
+declare dso_local void @bar(<8 x float>* %p)
Index: llvm/lib/IR/Verifier.cpp
===================================================================
--- llvm/lib/IR/Verifier.cpp
+++ llvm/lib/IR/Verifier.cpp
@@ -1732,13 +1732,26 @@
 
   verifyAttributeTypes(Attrs, V);
 
-  for (Attribute Attr : Attrs)
+  for (Attribute Attr : Attrs) {
     Assert(Attr.isStringAttribute() ||
            Attribute::canUseAsParamAttr(Attr.getKindAsEnum()),
            "Attribute '" + Attr.getAsString() +
                "' does not apply to parameters",
            V);
 
+    if (Attr.hasAttribute(Attribute::Alignment)) {
+      Align AttrAlign = Attr.getAlignment().valueOrOne();
+      // ArgFlagsTy::MemAlign only have 4 bits for alignment, so the
+      // alignment size should not exceed 2^15. Since encode(Align)
+      // would plus the shift value by 1, the alignment size should
+      // not exceed 2^14, otherwise it can NOT be properly lowered
+      Align MaxAlign(1 << 15);
+      Assert(AttrAlign < MaxAlign,
+             "Attribute '" + Attr.getAsString() + "' exceed the max size 2^14",
+             V);
+    }
+  }
+
   if (Attrs.hasAttribute(Attribute::ImmArg)) {
     Assert(Attrs.getNumAttributes() == 1,
            "Attribute 'immarg' is incompatible with other attributes", V);


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