[PATCH] D138634: GlobalIFunc: Make allowed constant expressions stricter

[Matt Arsenault via Phabricator via llvm-commits]

arsenm created this revision.
arsenm added reviewers: MaskRay, ibookstein, tejohnson, dexonsmith.
Herald added subscribers: StephenFan, hiraditya.
Herald added a project: All.
arsenm requested review of this revision.
Herald added a subscriber: wdng.
Herald added a project: LLVM.

This was allowing getelementptr with offsets, which doesn't make
sense. My initial attempt to use stripPointerCasts broke a few tests
involving aliases; add a new targeted verifier test for aliases.

      

This also provides the fix from D138537 <https://reviews.llvm.org/D138537> for free, and also adds
support for addrspacecast (D138538 <https://reviews.llvm.org/D138538>) for free. Merge the tests in from
those.

      

I'm not really sure why findBaseObject exists; it seems redundant with
stripPointerCasts* (I'm also not really sure why getelementptrs are
allowed off of functions).


https://reviews.llvm.org/D138634

Files:
  llvm/lib/IR/Globals.cpp
  llvm/test/Assembler/ifunc-addrspacecast.ll
  llvm/test/Assembler/ifunc-alias.ll
  llvm/test/Assembler/ifunc-unhandled-constantexpr.ll
  llvm/test/Verifier/ifunc-opaque.ll


Index: llvm/test/Verifier/ifunc-opaque.ll
===================================================================
--- /dev/null
+++ llvm/test/Verifier/ifunc-opaque.ll
@@ -0,0 +1,9 @@
+; RUN:  not llvm-as %s -o /dev/null 2>&1 | FileCheck %s
+
+define ptr @resolver() {
+  ret ptr null
+}
+
+; CHECK: IFunc must have a Function resolver
+; CHECK-NEXT: ptr @ifunc_getelementptr
+ at ifunc_getelementptr = ifunc void (), ptr getelementptr (i8, ptr @resolver, i32 4)
Index: llvm/test/Assembler/ifunc-unhandled-constantexpr.ll
===================================================================
--- /dev/null
+++ llvm/test/Assembler/ifunc-unhandled-constantexpr.ll
@@ -0,0 +1,12 @@
+; RUN: not llvm-as < %s 2>&1 | FileCheck %s
+
+; Make sure nothing asserts on an unhandled constantexpr for the
+; resolver.
+
+; CHECK: IFunc must have a Function resolver
+; CHECK-NEXT: ptr @ifunc_shl
+ at ifunc_shl = ifunc void (), ptr inttoptr (i64 shl (i64 ptrtoint (ptr @resolver to i64), i64 4) to ptr)
+
+define ptr @resolver() {
+  ret ptr null
+}
Index: llvm/test/Assembler/ifunc-alias.ll
===================================================================
--- /dev/null
+++ llvm/test/Assembler/ifunc-alias.ll
@@ -0,0 +1,12 @@
+; RUN: llvm-as < %s | llvm-dis | FileCheck %s
+
+; CHECK: @alias_resolver = internal alias i32 (i32), ptr @resolver
+ at alias_resolver = internal alias i32 (i32), ptr @resolver
+
+; CHECK: @ifunc_resolver_is_alias = internal ifunc i32 (i32), ptr @alias_resolver
+ at ifunc_resolver_is_alias = internal ifunc i32 (i32), ptr @alias_resolver
+
+; CHECK: define internal ptr @resolver() {
+define internal ptr @resolver() {
+  ret ptr null
+}
Index: llvm/test/Assembler/ifunc-addrspacecast.ll
===================================================================
--- /dev/null
+++ llvm/test/Assembler/ifunc-addrspacecast.ll
@@ -0,0 +1,9 @@
+; RUN: llvm-as < %s | llvm-dis | FileCheck %s
+
+; CHECK: @ifunc_addrspacecast_as1_to_as0 = ifunc void (), addrspacecast (ptr addrspace(1) @resolver_as1 to ptr)
+ at ifunc_addrspacecast_as1_to_as0 = ifunc void (), ptr addrspacecast (ptr addrspace(1) @resolver_as1 to ptr)
+
+; CHECK: define ptr @resolver_as1() addrspace(1) {
+define ptr @resolver_as1() addrspace(1) {
+  ret ptr null
+}
Index: llvm/lib/IR/Globals.cpp
===================================================================
--- llvm/lib/IR/Globals.cpp
+++ llvm/lib/IR/Globals.cpp
@@ -589,9 +589,7 @@
 }
 
 const Function *GlobalIFunc::getResolverFunction() const {
-  DenseSet<const GlobalAlias *> Aliases;
-  return dyn_cast<Function>(
-      findBaseObject(getResolver(), Aliases, [](const GlobalValue &) {}));
+  return dyn_cast<Function>(getResolver()->stripPointerCastsAndAliases());
 }
 
 void GlobalIFunc::applyAlongResolverPath(


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