diff options
| -rw-r--r-- | llvm/lib/Target/AArch64/AArch64TargetMachine.cpp | 15 | ||||
| -rw-r--r-- | llvm/test/CodeGen/AArch64/global-merge-minsize.ll | 21 |
2 files changed, 35 insertions, 1 deletions
diff --git a/llvm/lib/Target/AArch64/AArch64TargetMachine.cpp b/llvm/lib/Target/AArch64/AArch64TargetMachine.cpp index a9f7233413d..7ae055ad503 100644 --- a/llvm/lib/Target/AArch64/AArch64TargetMachine.cpp +++ b/llvm/lib/Target/AArch64/AArch64TargetMachine.cpp @@ -462,7 +462,20 @@ bool AArch64PassConfig::addPreISel() { EnableGlobalMerge == cl::BOU_TRUE) { bool OnlyOptimizeForSize = (TM->getOptLevel() < CodeGenOpt::Aggressive) && (EnableGlobalMerge == cl::BOU_UNSET); - addPass(createGlobalMergePass(TM, 4095, OnlyOptimizeForSize)); + + // Merging of extern globals is enabled by default on non-Mach-O as we + // expect it to be generally either beneficial or harmless. On Mach-O it + // is disabled as we emit the .subsections_via_symbols directive which + // means that merging extern globals is not safe. + bool MergeExternalByDefault = !TM->getTargetTriple().isOSBinFormatMachO(); + + // FIXME: extern global merging is only enabled when we optimise for size + // because there are some regressions with it also enabled for performance. + if (!OnlyOptimizeForSize) + MergeExternalByDefault = false; + + addPass(createGlobalMergePass(TM, 4095, OnlyOptimizeForSize, + MergeExternalByDefault)); } return false; diff --git a/llvm/test/CodeGen/AArch64/global-merge-minsize.ll b/llvm/test/CodeGen/AArch64/global-merge-minsize.ll new file mode 100644 index 00000000000..0d6b9ed31a2 --- /dev/null +++ b/llvm/test/CodeGen/AArch64/global-merge-minsize.ll @@ -0,0 +1,21 @@ +; RUN: llc %s -o - -verify-machineinstrs | FileCheck %s + +target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128" +target triple = "aarch64-arm-none-eabi" + +@global0 = dso_local local_unnamed_addr global i32 0, align 4 +@global1 = dso_local local_unnamed_addr global i32 0, align 4 + +define dso_local i32 @func() minsize optsize { +; CHECK-LABEL: @func +; CHECK: adrp x8, .L_MergedGlobals +; CHECK-NEXT: add x8, x8, :lo12:.L_MergedGlobals +; CHECK-NEXT: ldp w9, w8, [x8] +; CHECK-NEXT: add w0, w8, w9 +; CHECK-NEXT: ret +entry: + %0 = load i32, i32* @global0, align 4 + %1 = load i32, i32* @global1, align 4 + %add = add nsw i32 %1, %0 + ret i32 %add +} |
