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Revert r361460

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It regresses https://bugs.llvm.org/show_bug.cgi?id=38309 (represented
by the testcase test/Transforms/GlobalOpt/globalsra-multigep.ll).

llvm-svn: 361581
This commit is contained in:
Eli Friedman 2019-05-24 01:03:51 +00:00
parent 6543be6733
commit 05c23645a5
3 changed files with 6 additions and 50 deletions
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27
lib/Transforms/IPO/GlobalOpt.cpp
View File

@ -184,7 +184,7 @@ static bool IsSafeComputationToRemove(Value *V, const TargetLibraryInfo *TLI) {
/// This GV is a pointer root. Loop over all users of the global and clean up
/// any that obviously don't assign the global a value that isn't dynamically
/// allocated.
static bool CleanupPointerRootUsers(Value *V,
static bool CleanupPointerRootUsers(GlobalVariable *GV,
const TargetLibraryInfo *TLI) {
// A brief explanation of leak checkers. The goal is to find bugs where
// pointers are forgotten, causing an accumulating growth in memory
@ -202,7 +202,7 @@ static bool CleanupPointerRootUsers(Value *V,
SmallVector<std::pair<Instruction *, Instruction *>, 32> Dead;
// Constants can't be pointers to dynamically allocated memory.
for (Value::user_iterator UI = V->user_begin(), E = V->user_end();
for (Value::user_iterator UI = GV->user_begin(), E = GV->user_end();
UI != E;) {
User *U = *UI++;
if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
@ -232,9 +232,6 @@ static bool CleanupPointerRootUsers(Value *V,
Dead.push_back(std::make_pair(I, MTI));
}
} else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U)) {
if (CE->getOpcode() == Instruction::GetElementPtr) {
Changed |= CleanupPointerRootUsers(CE, TLI);
}
if (CE->use_empty()) {
CE->destroyConstant();
Changed = true;
@ -244,7 +241,7 @@ static bool CleanupPointerRootUsers(Value *V,
C->destroyConstant();
// This could have invalidated UI, start over from scratch.
Dead.clear();
CleanupPointerRootUsers(V, TLI);
CleanupPointerRootUsers(GV, TLI);
return true;
}
}
@ -394,22 +391,6 @@ static bool isSafeSROAGEP(User *U) {
[](User *UU) { return isSafeSROAElementUse(UU); });
}
/// Return true if the specified GEP is a safe user of a derived
/// expression from a global that we want to SROA.
static bool isSafeSubSROAGEP(User *U) {
// Check to see if this ConstantExpr GEP is SRA'able. In particular, we
// don't like < 3 operand CE's, and we don't like non-constant integer
// indices. This enforces that all uses are 'gep GV, 0, C, ...' for some
// value of C.
if (U->getNumOperands() < 3 || !isa<Constant>(U->getOperand(1)) ||
!cast<Constant>(U->getOperand(1))->isNullValue())
return false;
return llvm::all_of(U->users(),
[](User *UU) { return isSafeSROAElementUse(UU); });
}
/// Return true if the specified instruction is a safe user of a derived
/// expression from a global that we want to SROA.
static bool isSafeSROAElementUse(Value *V) {
@ -428,7 +409,7 @@ static bool isSafeSROAElementUse(Value *V) {
return SI->getOperand(0) != V;
// Otherwise, it must be a GEP. Check it and its users are safe to SRA.
return isa<GetElementPtrInst>(I) && isSafeSubSROAGEP(I);
return isa<GetElementPtrInst>(I) && isSafeSROAGEP(I);
}
/// Look at all uses of the global and decide whether it is safe for us to

11
test/Transforms/GlobalOpt/globalsra-multigep.ll
View File

@ -4,20 +4,13 @@ target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
@g_data = internal unnamed_addr global <{ [8 x i16], [8 x i16] }> <{ [8 x i16] [i16 16, i16 16, i16 16, i16 16, i16 16, i16 16, i16 16, i16 16], [8 x i16] zeroinitializer }>, align 16
; We normally cannot SRA here due to the second gep meaning the access to g_data may be to either element,
; unless the value is always zero.
; CHECK: @g_data.0 = internal unnamed_addr constant [8 x i16] [i16 16, i16 16, i16 16, i16 16, i16 16, i16 16, i16 16, i16 16], align 16
; We cannot SRA here due to the second gep meaning the access to g_data may be to either element
; CHECK: @g_data = internal unnamed_addr constant <{ [8 x i16], [8 x i16] }>
define i16 @test(i64 %a1) {
entry:
%g1 = getelementptr inbounds <{ [8 x i16], [8 x i16] }>, <{ [8 x i16], [8 x i16] }>* @g_data, i64 0, i32 0
%arrayidx.i = getelementptr inbounds [8 x i16], [8 x i16]* %g1, i64 0, i64 %a1
%r = load i16, i16* %arrayidx.i, align 2
; CHECK-NOT: getelementptr inbounds <{ [8 x i16], [8 x i16] }>, <{ [8 x i16], [8 x i16] }>* @g_data, i64 0, i32 0
; CHECK: %arrayidx.i = getelementptr inbounds [8 x i16], [8 x i16]* @g_data.0, i64 0, i64 %a1
ret i16 %r
}

18
test/Transforms/GlobalOpt/globalsra-struct.ll
View File

@ -1,18 +0,0 @@
; RUN: opt < %s -globalopt -S | FileCheck %s
%struct.Expr = type { [1 x i32], i32 }
@e = internal global %struct.Expr zeroinitializer, align 4
; CHECK-NOT: @e = internal global %struct.Expr zeroinitializer, align 4
define dso_local i32 @foo(i32 %i) {
entry:
%i.addr = alloca i32, align 4
store i32 %i, i32* %i.addr, align 4
%0 = load i32, i32* %i.addr, align 4
%arrayidx = getelementptr inbounds [1 x i32], [1 x i32]* getelementptr inbounds (%struct.Expr, %struct.Expr* @e, i32 0, i32 0), i32 0, i32 %0
store i32 57005, i32* %arrayidx, align 4
%1 = load i32, i32* getelementptr inbounds (%struct.Expr, %struct.Expr* @e, i32 0, i32 1), align 4
ret i32 %1
; CHECK: ret i32 0
}