[llvm] r277331 - [AArch64] Return the correct size for TLSDESC_CALLSEQ
Diana Picus via llvm-commits
llvm-commits at lists.llvm.org
Mon Aug 1 01:38:50 PDT 2016
Author: rovka
Date: Mon Aug 1 03:38:49 2016
New Revision: 277331
URL: http://llvm.org/viewvc/llvm-project?rev=277331&view=rev
Log:
[AArch64] Return the correct size for TLSDESC_CALLSEQ
The branch relaxation pass is computing the wrong offsets because it assumes
TLSDESC_CALLSEQ eats up 4 bytes, when in fact it is lowered to an instruction
sequence taking up 16 bytes. This can become a problem in huge files with lots
of TLS accesses, as it may slowly move branch targets out of the range computed
by the branch relaxation pass.
Fixes PR24234 https://llvm.org/bugs/show_bug.cgi?id=24234
Differential Revision: https://reviews.llvm.org/D22870
Added:
llvm/trunk/test/CodeGen/MIR/AArch64/inst-size-tlsdesc-callseq.mir
Modified:
llvm/trunk/lib/Target/AArch64/AArch64InstrInfo.cpp
Modified: llvm/trunk/lib/Target/AArch64/AArch64InstrInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AArch64/AArch64InstrInfo.cpp?rev=277331&r1=277330&r2=277331&view=diff
==============================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64InstrInfo.cpp (original)
+++ llvm/trunk/lib/Target/AArch64/AArch64InstrInfo.cpp Mon Aug 1 03:38:49 2016
@@ -56,6 +56,9 @@ unsigned AArch64InstrInfo::getInstSizeIn
case TargetOpcode::IMPLICIT_DEF:
case TargetOpcode::KILL:
return 0;
+ case AArch64::TLSDESC_CALLSEQ:
+ // This gets lowered to an instruction sequence which takes 16 bytes
+ return 16;
}
llvm_unreachable("getInstSizeInBytes()- Unable to determin insn size");
Added: llvm/trunk/test/CodeGen/MIR/AArch64/inst-size-tlsdesc-callseq.mir
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/MIR/AArch64/inst-size-tlsdesc-callseq.mir?rev=277331&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/MIR/AArch64/inst-size-tlsdesc-callseq.mir (added)
+++ llvm/trunk/test/CodeGen/MIR/AArch64/inst-size-tlsdesc-callseq.mir Mon Aug 1 03:38:49 2016
@@ -0,0 +1,84 @@
+# RUN: llc -mtriple=aarch64-unknown -run-pass aarch64-branch-relax -aarch64-tbz-offset-bits=4 %s -o - | FileCheck %s
+--- |
+ ; ModuleID = 'test.ll'
+ source_filename = "test.ll"
+ target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
+ target triple = "aarch64-unknown"
+
+ @ThreadLocalGlobal = external thread_local local_unnamed_addr global i32, align 8
+
+ define i32 @test_tlsdesc_callseq_length(i32 %in) {
+ %val = and i32 %in, 1
+ %tst = icmp eq i32 %val, 0
+ br i1 %tst, label %true, label %false
+
+ true: ; preds = %0
+ %1 = load i32, i32* @ThreadLocalGlobal, align 8
+ ret i32 %1
+
+ false: ; preds = %0
+ ret i32 0
+ }
+
+...
+---
+# CHECK-LABEL: name:{{.*}}test_tlsdesc_callseq_length
+# If the size of TLSDESC_CALLSEQ is computed correctly, that will push
+# the bb.2.false block too far away from the TBNZW, so the branch will
+# have to be relaxed (note that we're using -aarch64-tbz-offset-bits to
+# constrain the range that can be reached with the TBNZW to something smaller
+# than what TLSDESC_CALLSEQ is lowered to).
+# CHECK: TBZW killed %w0, 0, %bb.1.true
+# CHECK: B %bb.2.false
+name: test_tlsdesc_callseq_length
+alignment: 2
+exposesReturnsTwice: false
+hasInlineAsm: false
+allVRegsAllocated: true
+isSSA: false
+tracksRegLiveness: false
+tracksSubRegLiveness: false
+liveins:
+ - { reg: '%w0' }
+frameInfo:
+ isFrameAddressTaken: false
+ isReturnAddressTaken: false
+ hasStackMap: false
+ hasPatchPoint: false
+ stackSize: 16
+ offsetAdjustment: 0
+ maxAlignment: 16
+ adjustsStack: false
+ hasCalls: true
+ maxCallFrameSize: 0
+ hasOpaqueSPAdjustment: false
+ hasVAStart: false
+ hasMustTailInVarArgFunc: false
+stack:
+ - { id: 0, type: spill-slot, offset: -16, size: 8, alignment: 16, callee-saved-register: '%lr' }
+body: |
+ bb.0 (%ir-block.0):
+ successors: %bb.1.true, %bb.2.false
+ liveins: %w0, %lr
+
+ TBNZW killed %w0, 0, %bb.2.false
+
+ bb.1.true:
+ liveins: %lr
+
+ early-clobber %sp = frame-setup STRXpre killed %lr, %sp, -16 :: (store 8 into %stack.0)
+ frame-setup CFI_INSTRUCTION def_cfa_offset 16
+ frame-setup CFI_INSTRUCTION offset %w30, -16
+ TLSDESC_CALLSEQ target-flags(aarch64-tls) @ThreadLocalGlobal, implicit-def dead %lr, implicit-def %x0, implicit-def dead %x1
+ %x8 = MRS 56962
+ %w0 = LDRWroX killed %x8, killed %x0, 0, 0 :: (load 4 from @ThreadLocalGlobal, align 8)
+ early-clobber %sp, %lr = LDRXpost %sp, 16 :: (load 8 from %stack.0)
+ RET killed %lr, implicit killed %w0
+
+ bb.2.false:
+ liveins: %lr
+
+ %w0 = ORRWrs %wzr, %wzr, 0
+ RET killed %lr, implicit killed %w0
+
+...
More information about the llvm-commits
mailing list