Fix PR19136: [ARM] Fix Folding SP Update into vpush/vpop

Sicne MBB->computeRegisterLivenes() returns Dead for sub regs like s0,
d0 is used in vpop instead of updating sp, which causes s0 dead before
its use.

This patch checks the liveness of each subreg to make sure the reg is
actually dead.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204411 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/ARM/ARMBaseInstrInfo.cpp b/lib/Target/ARM/ARMBaseInstrInfo.cpp
index 21b8e6b870503e15a22212ea02d538bb2a1839f8..4c69a90c4b63373efd9b212673cff2afcff769ad 100644 (file)
--- a/lib/Target/ARM/ARMBaseInstrInfo.cpp
+++ b/lib/Target/ARM/ARMBaseInstrInfo.cpp
@@ -1866,6 +1866,15 @@ void llvm::emitARMRegPlusImmediate(MachineBasicBlock &MBB,
   }
 }
 
+static bool isAnySubRegLive(unsigned Reg, const TargetRegisterInfo *TRI,
+                      MachineInstr *MI) {
+  for (MCSubRegIterator Subreg(Reg, TRI, /* IncludeSelf */ true);
+       Subreg.isValid(); ++Subreg)
+    if (MI->getParent()->computeRegisterLiveness(TRI, *Subreg, MI) !=
+        MachineBasicBlock::LQR_Dead)
+      return true;
+  return false;
+}
 bool llvm::tryFoldSPUpdateIntoPushPop(const ARMSubtarget &Subtarget,
                                       MachineFunction &MF, MachineInstr *MI,
                                       unsigned NumBytes) {
@@ -1920,7 +1929,6 @@ bool llvm::tryFoldSPUpdateIntoPushPop(const ARMSubtarget &Subtarget,
   for (int i = MI->getNumOperands() - 1; i >= RegListIdx; --i)
     RegList.push_back(MI->getOperand(i));
 
-  MachineBasicBlock *MBB = MI->getParent();
   const TargetRegisterInfo *TRI = MF.getRegInfo().getTargetRegisterInfo();
   const MCPhysReg *CSRegs = TRI->getCalleeSavedRegs(&MF);
 
@@ -1941,9 +1949,11 @@ bool llvm::tryFoldSPUpdateIntoPushPop(const ARMSubtarget &Subtarget,
     // registers live within the function we might clobber a return value
     // register; the other way a register can be live here is if it's
     // callee-saved.
+    // TODO: Currently, computeRegisterLiveness() does not report "live" if a
+    // sub reg is live. When computeRegisterLiveness() works for sub reg, it
+    // can replace isAnySubRegLive().
     if (isCalleeSavedRegister(CurReg, CSRegs) ||
-        MBB->computeRegisterLiveness(TRI, CurReg, MI) !=
-            MachineBasicBlock::LQR_Dead) {
+        isAnySubRegLive(CurReg, TRI, MI)) {
       // VFP pops don't allow holes in the register list, so any skip is fatal
       // for our transformation. GPR pops do, so we should just keep looking.
       if (IsVFPPushPop)

diff --git a/test/CodeGen/ARM/fold-stack-adjust.ll b/test/CodeGen/ARM/fold-stack-adjust.ll
index feac793f4f8aa422f5e0f23dc8792ebe428b17c4..695a20b5976d575e7f15ef0383186ab9c401e81f 100644 (file)
--- a/test/CodeGen/ARM/fold-stack-adjust.ll
+++ b/test/CodeGen/ARM/fold-stack-adjust.ll
@@ -1,6 +1,7 @@
 ; RUN: llc -mtriple=thumbv7-apple-none-macho < %s | FileCheck %s
 ; RUN: llc -mtriple=thumbv6m-apple-none-macho -disable-fp-elim < %s | FileCheck %s --check-prefix=CHECK-T1
 ; RUN: llc -mtriple=thumbv7-apple-darwin-ios -disable-fp-elim < %s | FileCheck %s --check-prefix=CHECK-IOS
+; RUN: llc -mtriple=thumbv7--linux-gnueabi -disable-fp-elim < %s | FileCheck %s --check-prefix=CHECK-LINUX
 
 
 declare void @bar(i8*)
@@ -185,3 +186,33 @@ define void @test_varsize(...) minsize {
   call void @bar(i8* %var)
   ret void
 }
+
+%"MyClass" = type { i8*, i32, i32, float, float, float, [2 x i8], i32, i32* }
+
+declare float @foo()
+
+declare void @bar3()
+
+declare %"MyClass"* @bar2(%"MyClass"* returned, i16*, i32, float, float, i32, i32, i1 zeroext, i1 zeroext, i32)
+
+define fastcc float @check_vfp_no_return_clobber2(i16* %r, i16* %chars, i32 %length, i1 zeroext %flag) minsize {
+entry:
+; CHECK-LINUX-LABEL: check_vfp_no_return_clobber2
+; CHECK-LINUX: vpush   {d0, d1, d2, d3, d4, d5, d6, d7, d8}
+; CHECK-NOT: sub sp,
+; ...
+; CHECK-LINUX: add sp
+; CHECK-LINUX: vpop {d8}
+  %run = alloca %"MyClass", align 4
+  %call = call %"MyClass"* @bar2(%"MyClass"* %run, i16* %chars, i32 %length, float 0.000000e+00, float 0.000000e+00, i32 1, i32 1, i1 zeroext false, i1 zeroext true, i32 3)
+  %call1 = call float @foo()
+  %cmp = icmp eq %"MyClass"* %run, null
+  br i1 %cmp, label %exit, label %if.then
+
+if.then:                                          ; preds = %entry
+  call void @bar3()
+  br label %exit
+
+exit:                                             ; preds = %if.then, %entry
+  ret float %call1
+}