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[GlobalMerge] add a command to force global merge #168231

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[GlobalMerge] add a command to force global merge #168231

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10 changes: 9 additions & 1 deletion llvm/lib/CodeGen/GlobalMerge.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -111,6 +111,12 @@ EnableGlobalMerge("enable-global-merge", cl::Hidden,
cl::desc("Enable the global merge pass"),
cl::init(true));

static cl::opt<bool> ForceEnableGlobalMerge(
"force-enable-global-merge", cl::Hidden,
cl::desc(
"Force enable the global merge, regardless of the optimization level"),
cl::init(false));

static cl::opt<unsigned>
GlobalMergeMaxOffset("global-merge-max-offset", cl::Hidden,
cl::desc("Set maximum offset for global merge pass"),
Expand Down Expand Up @@ -374,7 +380,9 @@ bool GlobalMergeImpl::doMerge(SmallVectorImpl<GlobalVariable *> &Globals,
Function *ParentFn = I->getParent()->getParent();

// If we're only optimizing for size, ignore non-minsize functions.
if (Opt.SizeOnly && !ParentFn->hasMinSize())
// And add a config to force global merge
if (!ForceEnableGlobalMerge &&
(Opt.SizeOnly && !ParentFn->hasMinSize()))
continue;

size_t UGSIdx = GlobalUsesByFunction[ParentFn];
Expand Down
23 changes: 23 additions & 0 deletions llvm/test/CodeGen/ARM/force-global-merge.ll
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@@ -0,0 +1,23 @@
; RUN: llc -mtriple=arm-eabi -force-enable-global-merge %s -o - | FileCheck %s

@g_value1 = dso_local local_unnamed_addr global i32 0, align 4
@g_value2 = dso_local local_unnamed_addr global i32 0, align 4
@g_value3 = dso_local local_unnamed_addr global i32 0, align 4
@g_value4 = dso_local local_unnamed_addr global i32 0, align 4

define dso_local i32 @foo1() local_unnamed_addr {
entry:
%0 = load i32, ptr @g_value1, align 4
%1 = load i32, ptr @g_value2, align 4
%2 = load i32, ptr @g_value3, align 4
%3 = load i32, ptr @g_value4, align 4
%call = tail call i32 @foo(i32 %0, i32 %1, i32 %2, i32 %3)
ret i32 %call
}

declare i32 @foo(i32, i32, i32, i32)

; CHECK: ldr [[BASE:r[0-9]+]], .LCPI0_0
; CHECK: ldm [[BASE]], {[[R0:r[0-9]+]], [[R1:r[0-9]+]], [[R2:r[0-9]+]], [[R3:r[0-9]+]]}
; CHECK: .LCPI0_0:
; CHECK-NEXT: .long .L_MergedGlobals
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