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| author | Peter Collingbourne <peter@pcc.me.uk> | 2015-04-23 20:31:32 +0000 |
|---|---|---|
| committer | Peter Collingbourne <peter@pcc.me.uk> | 2015-04-23 20:31:32 +0000 |
| commit | 1ad0f741557afc28b626cb6fde8113e8aa997332 (patch) | |
| tree | 56611039e52ae0b9d78656faababb6c0da813fe9 | |
| parent | d9a479e5a0364ffd04b9ff2af3d2baaa4cd27a6d (diff) | |
ARM: When re-creating a branch via InsertBranch, preserve CPSR flags.
In particular, this preserves the kill flag, which allows the Thumb2 cbn?z
optimization to be applied in cases where a branch has been re-created after
the live variables analysis pass, e.g. by the machine block placement pass.
This appears to be low risk; a number of other targets seem to already be
doing something similar, e.g. AArch64, PowerPC.
Differential Revision: http://reviews.llvm.org/D9184
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235639 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | lib/Target/ARM/ARMBaseInstrInfo.cpp | 6 | ||||
| -rw-r--r-- | test/CodeGen/ARM/sjlj-prepare-critical-edge.ll | 2 | ||||
| -rw-r--r-- | test/CodeGen/Thumb2/v8_IT_5.ll | 3 |
3 files changed, 6 insertions, 5 deletions
diff --git a/lib/Target/ARM/ARMBaseInstrInfo.cpp b/lib/Target/ARM/ARMBaseInstrInfo.cpp index 93742dd6c7..a370ab3767 100644 --- a/lib/Target/ARM/ARMBaseInstrInfo.cpp +++ b/lib/Target/ARM/ARMBaseInstrInfo.cpp @@ -410,6 +410,8 @@ ARMBaseInstrInfo::InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB, assert((Cond.size() == 2 || Cond.size() == 0) && "ARM branch conditions have two components!"); + // For conditional branches, we use addOperand to preserve CPSR flags. + if (!FBB) { if (Cond.empty()) { // Unconditional branch? if (isThumb) @@ -418,13 +420,13 @@ ARMBaseInstrInfo::InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB, BuildMI(&MBB, DL, get(BOpc)).addMBB(TBB); } else BuildMI(&MBB, DL, get(BccOpc)).addMBB(TBB) - .addImm(Cond[0].getImm()).addReg(Cond[1].getReg()); + .addImm(Cond[0].getImm()).addOperand(Cond[1]); return 1; } // Two-way conditional branch. BuildMI(&MBB, DL, get(BccOpc)).addMBB(TBB) - .addImm(Cond[0].getImm()).addReg(Cond[1].getReg()); + .addImm(Cond[0].getImm()).addOperand(Cond[1]); if (isThumb) BuildMI(&MBB, DL, get(BOpc)).addMBB(FBB).addImm(ARMCC::AL).addReg(0); else diff --git a/test/CodeGen/ARM/sjlj-prepare-critical-edge.ll b/test/CodeGen/ARM/sjlj-prepare-critical-edge.ll index dd0a0a0803..f85203e381 100644 --- a/test/CodeGen/ARM/sjlj-prepare-critical-edge.ll +++ b/test/CodeGen/ARM/sjlj-prepare-critical-edge.ll @@ -79,7 +79,7 @@ declare void @terminatev() ; CHECK: str r0, [sp, [[OFFSET:#[0-9]+]]] ; CHECK: ldr [[R0:r[0-9]+]], [sp, [[OFFSET]]] ; CHECK: {{.*}}@ %do.body.i.i.i -; CHECK: cmp [[R0]], #0 +; CHECK: cbz [[R0]] %"class.std::__1::basic_string" = type { %"class.std::__1::__compressed_pair" } %"class.std::__1::__compressed_pair" = type { %"class.std::__1::__libcpp_compressed_pair_imp" } diff --git a/test/CodeGen/Thumb2/v8_IT_5.ll b/test/CodeGen/Thumb2/v8_IT_5.ll index 2da75ad214..78b80d7dcd 100644 --- a/test/CodeGen/Thumb2/v8_IT_5.ll +++ b/test/CodeGen/Thumb2/v8_IT_5.ll @@ -3,8 +3,7 @@ ; CHECK: it ne ; CHECK-NEXT: cmpne ; CHECK-NEXT: bne [[JUMPTARGET:.LBB[0-9]+_[0-9]+]] -; CHECK: cmp -; CHECK-NEXT: beq +; CHECK: cbz ; CHECK-NEXT: %if.else163 ; CHECK-NEXT: mov.w ; CHECK-NEXT: b |