104 lines
4.2 KiB
Diff
104 lines
4.2 KiB
Diff
From 97ab1917845fa9426ba913139fc8a007cba1d7ce Mon Sep 17 00:00:00 2001
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From: Nikita Popov <npopov@redhat.com>
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Date: Mon, 27 May 2024 08:54:11 +0200
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Subject: [PATCH] [PPCMergeStringPool] Only replace constant once (#92996)
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In #88846 I changed this code to use RAUW to perform the replacement
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instead of manual updates -- but kept the outer loop, which means we try
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to perform RAUW once per user. However, some of the users might be freed
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by the RAUW operation, resulting in use-after-free.
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The case where this happens is constant users where the replacement
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might result in the destruction of the original constant.
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Fixes https://github.com/llvm/llvm-project/issues/92991.
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(cherry picked from commit 9f85bc834b07ebfec9e5e02deb9255a0f6ec5cc7)
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---
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.../lib/Target/PowerPC/PPCMergeStringPool.cpp | 37 ++++---------------
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.../PowerPC/mergeable-string-pool-pr92991.ll | 20 ++++++++++
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2 files changed, 27 insertions(+), 30 deletions(-)
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create mode 100644 llvm/test/CodeGen/PowerPC/mergeable-string-pool-pr92991.ll
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diff --git a/llvm/lib/Target/PowerPC/PPCMergeStringPool.cpp b/llvm/lib/Target/PowerPC/PPCMergeStringPool.cpp
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index ebd876d50c44e..0830b02370cd0 100644
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--- a/llvm/lib/Target/PowerPC/PPCMergeStringPool.cpp
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+++ b/llvm/lib/Target/PowerPC/PPCMergeStringPool.cpp
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@@ -290,13 +290,6 @@ bool PPCMergeStringPool::mergeModuleStringPool(Module &M) {
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return true;
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}
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-static bool userHasOperand(User *TheUser, GlobalVariable *GVOperand) {
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- for (Value *Op : TheUser->operands())
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- if (Op == GVOperand)
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- return true;
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- return false;
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-}
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-
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// For pooled strings we need to add the offset into the pool for each string.
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// This is done by adding a Get Element Pointer (GEP) before each user. This
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// function adds the GEP.
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@@ -307,29 +300,13 @@ void PPCMergeStringPool::replaceUsesWithGEP(GlobalVariable *GlobalToReplace,
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Indices.push_back(ConstantInt::get(Type::getInt32Ty(*Context), 0));
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Indices.push_back(ConstantInt::get(Type::getInt32Ty(*Context), ElementIndex));
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- // Need to save a temporary copy of each user list because we remove uses
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- // as we replace them.
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- SmallVector<User *> Users;
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- for (User *CurrentUser : GlobalToReplace->users())
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- Users.push_back(CurrentUser);
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-
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- for (User *CurrentUser : Users) {
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- // The user was not found so it must have been replaced earlier.
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- if (!userHasOperand(CurrentUser, GlobalToReplace))
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- continue;
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-
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- // We cannot replace operands in globals so we ignore those.
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- if (isa<GlobalValue>(CurrentUser))
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- continue;
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-
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- Constant *ConstGEP = ConstantExpr::getInBoundsGetElementPtr(
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- PooledStructType, GPool, Indices);
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- LLVM_DEBUG(dbgs() << "Replacing this global:\n");
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- LLVM_DEBUG(GlobalToReplace->dump());
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- LLVM_DEBUG(dbgs() << "with this:\n");
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- LLVM_DEBUG(ConstGEP->dump());
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- GlobalToReplace->replaceAllUsesWith(ConstGEP);
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- }
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+ Constant *ConstGEP =
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+ ConstantExpr::getInBoundsGetElementPtr(PooledStructType, GPool, Indices);
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+ LLVM_DEBUG(dbgs() << "Replacing this global:\n");
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+ LLVM_DEBUG(GlobalToReplace->dump());
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+ LLVM_DEBUG(dbgs() << "with this:\n");
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+ LLVM_DEBUG(ConstGEP->dump());
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+ GlobalToReplace->replaceAllUsesWith(ConstGEP);
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}
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} // namespace
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diff --git a/llvm/test/CodeGen/PowerPC/mergeable-string-pool-pr92991.ll b/llvm/test/CodeGen/PowerPC/mergeable-string-pool-pr92991.ll
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new file mode 100644
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index 0000000000000..4e9c69e5fe4cf
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--- /dev/null
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+++ b/llvm/test/CodeGen/PowerPC/mergeable-string-pool-pr92991.ll
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@@ -0,0 +1,20 @@
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+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
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+; RUN: llc -mtriple=powerpc64le-unknown-linux-gnu < %s | FileCheck %s
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+
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+@g = private constant [4 x i32] [i32 122, i32 67, i32 35, i32 56]
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+@g2 = private constant [1 x i64] [i64 1], align 8
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+
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+define void @test(ptr %p, ptr %p2) {
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+; CHECK-LABEL: test:
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+; CHECK: # %bb.0:
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+; CHECK-NEXT: addis 5, 2, .L__ModuleStringPool@toc@ha
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+; CHECK-NEXT: addi 5, 5, .L__ModuleStringPool@toc@l
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+; CHECK-NEXT: addi 6, 5, 12
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+; CHECK-NEXT: std 6, 0(3)
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+; CHECK-NEXT: addi 3, 5, 16
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+; CHECK-NEXT: std 3, 0(4)
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+; CHECK-NEXT: blr
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+ store ptr getelementptr inbounds ([4 x i32], ptr @g, i64 0, i64 1), ptr %p
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+ store ptr getelementptr inbounds ([4 x i32], ptr @g, i64 0, i64 2), ptr %p2
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+ ret void
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+}
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