[llvm] f0b61f7 - Revert "[GlobalOpt] Don't replace alias with aliasee if either alias/aliasee may be preemptible"
Arthur Eubanks via llvm-commits
llvm-commits at lists.llvm.org
Thu Mar 3 11:05:41 PST 2022
Author: Arthur Eubanks
Date: 2022-03-03T11:04:14-08:00
New Revision: f0b61f795758ae8deba8e7f940b6df42639f91dc
URL: https://github.com/llvm/llvm-project/commit/f0b61f795758ae8deba8e7f940b6df42639f91dc
DIFF: https://github.com/llvm/llvm-project/commit/f0b61f795758ae8deba8e7f940b6df42639f91dc.diff
LOG: Revert "[GlobalOpt] Don't replace alias with aliasee if either alias/aliasee may be preemptible"
This reverts commit 30e8f83c84c5a302a559722fc0d2973dc3f425ee.
Causes huge compile time regressions on certain large files. Will followup offline with author.
Added:
Modified:
llvm/docs/LangRef.rst
llvm/lib/Transforms/IPO/GlobalOpt.cpp
llvm/test/Transforms/GlobalOpt/2009-02-15-ResolveAlias.ll
llvm/test/Transforms/GlobalOpt/alias-resolve.ll
llvm/test/Transforms/GlobalOpt/alias-used-address-space.ll
llvm/test/Transforms/GlobalOpt/alias-used.ll
Removed:
################################################################################
diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
index 495d5a3cfd327..be10ff12911a9 100644
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -894,11 +894,6 @@ some can only be checked when producing an object file:
* No global value in the expression can be a declaration, since that
would require a relocation, which is not possible.
-* If either the alias or the aliasee may be replaced by a symbol outside the
- module at link time or runtime, any optimization cannot replace the alias with
- the aliasee, since the behavior may be
diff erent. The alias may be used as a
- name guaranteed to point to the content in the current module.
-
.. _langref_ifunc:
IFuncs
diff --git a/llvm/lib/Transforms/IPO/GlobalOpt.cpp b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
index 1cb32e32c895a..a29d4f60a653e 100644
--- a/llvm/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
@@ -2225,13 +2225,6 @@ OptimizeGlobalAliases(Module &M,
for (GlobalValue *GV : Used.used())
Used.compilerUsedErase(GV);
- // Return whether GV is explicitly or implicitly dso_local and not replaceable
- // by another definition in the current linkage unit.
- auto IsModuleLocal = [](GlobalValue &GV) {
- return !GlobalValue::isInterposableLinkage(GV.getLinkage()) &&
- (GV.isDSOLocal() || GV.isImplicitDSOLocal());
- };
-
for (GlobalAlias &J : llvm::make_early_inc_range(M.aliases())) {
// Aliases without names cannot be referenced outside this module.
if (!J.hasName() && !J.isDeclaration() && !J.hasLocalLinkage())
@@ -2243,20 +2236,18 @@ OptimizeGlobalAliases(Module &M,
}
// If the alias can change at link time, nothing can be done - bail out.
- if (!IsModuleLocal(J))
+ if (J.isInterposable())
continue;
Constant *Aliasee = J.getAliasee();
GlobalValue *Target = dyn_cast<GlobalValue>(Aliasee->stripPointerCasts());
// We can't trivially replace the alias with the aliasee if the aliasee is
// non-trivial in some way. We also can't replace the alias with the aliasee
- // if the aliasee may be preemptible at runtime. On ELF, a non-preemptible
- // alias can be used to access the definition as if preemption did not
- // happen.
+ // if the aliasee is interposable because aliases point to the local
+ // definition.
// TODO: Try to handle non-zero GEPs of local aliasees.
- if (!Target || !IsModuleLocal(*Target))
+ if (!Target || Target->isInterposable())
continue;
-
Target->removeDeadConstantUsers();
// Make all users of the alias use the aliasee instead.
diff --git a/llvm/test/Transforms/GlobalOpt/2009-02-15-ResolveAlias.ll b/llvm/test/Transforms/GlobalOpt/2009-02-15-ResolveAlias.ll
index ce7d4fcb8e253..c29753385a59c 100644
--- a/llvm/test/Transforms/GlobalOpt/2009-02-15-ResolveAlias.ll
+++ b/llvm/test/Transforms/GlobalOpt/2009-02-15-ResolveAlias.ll
@@ -2,13 +2,13 @@
define internal void @f() {
; CHECK-NOT: @f(
-; CHECK: define dso_local void @a
+; CHECK: define void @a
ret void
}
- at a = dso_local alias void (), void ()* @f
+ at a = alias void (), void ()* @f
-define hidden void @g() {
+define void @g() {
call void() @a()
ret void
}
diff --git a/llvm/test/Transforms/GlobalOpt/alias-resolve.ll b/llvm/test/Transforms/GlobalOpt/alias-resolve.ll
index efac61200a3ef..b4bee769e93d2 100644
--- a/llvm/test/Transforms/GlobalOpt/alias-resolve.ll
+++ b/llvm/test/Transforms/GlobalOpt/alias-resolve.ll
@@ -1,19 +1,16 @@
; RUN: opt < %s -passes=globalopt -S | FileCheck %s
@foo1 = alias void (), void ()* @foo2
-;; foo2 is dso_local and non-weak. Resolved.
; CHECK: @foo1 = alias void (), void ()* @bar2
- at foo2 = dso_local alias void(), void()* @bar1
-;; bar1 is dso_local and non-weak. Resolved.
-; CHECK: @foo2 = dso_local alias void (), void ()* @bar2
+ at foo2 = alias void(), void()* @bar1
+; CHECK: @foo2 = alias void (), void ()* @bar2
- at bar1 = dso_local alias void (), void ()* @bar2
-; CHECK: @bar1 = dso_local alias void (), void ()* @bar2
+ at bar1 = alias void (), void ()* @bar2
+; CHECK: @bar1 = alias void (), void ()* @bar2
- at weak1 = weak dso_local alias void (), void ()* @bar2
-;; weak1 may be replaced with another definition in the linkage unit. Not resolved.
-; CHECK: @weak1 = weak dso_local alias void (), void ()* @bar2
+ at weak1 = weak alias void (), void ()* @bar2
+; CHECK: @weak1 = weak alias void (), void ()* @bar2
@bar4 = private unnamed_addr constant [2 x i8*] zeroinitializer
@foo4 = weak_odr unnamed_addr alias i8*, getelementptr inbounds ([2 x i8*], [2 x i8*]* @bar4, i32 0, i32 1)
@@ -22,10 +19,10 @@
@priva = private alias void (), void ()* @bar5
; CHECK: @priva = private alias void (), void ()* @bar5
-define dso_local void @bar2() {
+define void @bar2() {
ret void
}
-; CHECK: define dso_local void @bar2()
+; CHECK: define void @bar2()
define weak void @bar5() {
ret void
@@ -35,32 +32,27 @@ define weak void @bar5() {
define void @baz() {
entry:
call void @foo1()
-;; foo1 is dso_preemptable. Not resolved.
-; CHECK: call void @foo1()
+; CHECK: call void @bar2()
call void @foo2()
-;; foo2 is dso_local and non-weak. Resolved.
; CHECK: call void @bar2()
call void @bar1()
-;; bar1 is dso_local and non-weak. Resolved.
; CHECK: call void @bar2()
call void @weak1()
-;; weak1 is weak. Not resolved.
; CHECK: call void @weak1()
call void @priva()
-;; priva has a local linkage. Resolved.
; CHECK: call void @priva()
ret void
}
- at foo3 = dso_local alias void (), void ()* @bar3
+ at foo3 = alias void (), void ()* @bar3
; CHECK-NOT: bar3
define internal void @bar3() {
ret void
}
-;CHECK: define dso_local void @foo3
+;CHECK: define void @foo3
diff --git a/llvm/test/Transforms/GlobalOpt/alias-used-address-space.ll b/llvm/test/Transforms/GlobalOpt/alias-used-address-space.ll
index daf5acd8446c6..d119bfb305063 100644
--- a/llvm/test/Transforms/GlobalOpt/alias-used-address-space.ll
+++ b/llvm/test/Transforms/GlobalOpt/alias-used-address-space.ll
@@ -2,7 +2,7 @@
target datalayout = "p:32:32:32-p1:16:16:16"
- at c = hidden addrspace(1) global i8 42
+ at c = addrspace(1) global i8 42
@i = internal addrspace(1) global i8 42
diff --git a/llvm/test/Transforms/GlobalOpt/alias-used.ll b/llvm/test/Transforms/GlobalOpt/alias-used.ll
index d8b7a765ed30f..73dd604f2a71d 100644
--- a/llvm/test/Transforms/GlobalOpt/alias-used.ll
+++ b/llvm/test/Transforms/GlobalOpt/alias-used.ll
@@ -1,6 +1,6 @@
; RUN: opt < %s -passes=globalopt -S | FileCheck %s
- at c = dso_local global i8 42
+ at c = global i8 42
@i = internal global i8 42
; CHECK: @ia = internal global i8 42
@@ -30,7 +30,7 @@
@ca = internal alias i8, i8* @c
; CHECK: @ca = internal alias i8, i8* @c
-define hidden void @f() {
+define void @f() {
ret void
}
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