From a0288535408cb58797a27465fed838753fcc6238 Mon Sep 17 00:00:00 2001
From: Saleem Abdulrasool <compnerd@compnerd.org>
Date: Thu, 21 Apr 2016 23:53:19 +0000
Subject: [PATCH] ARM: restrict register class for WIN__DBZCHK

WIN__DBZCHK will insert a CBZ instruction into the stream.  This instruction
reserves 3 bits for the condition register (rn).  As such, we must ensure that
we restrict the register to a low register.  Use the tGPR class instead of GPR
to ensure that this is properly constrained.  In debug builds, we would attempt
to use lr as a condition register which would silently get truncated with no
hint that the register selection was incorrect.

llvm-svn: 267080
---
 llvm/lib/Target/ARM/ARMInstrInfo.td     |  4 +--
 llvm/test/CodeGen/ARM/Windows/dbzchk.ll | 47 +++++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/llvm/lib/Target/ARM/ARMInstrInfo.td b/llvm/lib/Target/ARM/ARMInstrInfo.td
index 3f32dd7..25472b5 100644
--- a/llvm/lib/Target/ARM/ARMInstrInfo.td
+++ b/llvm/lib/Target/ARM/ARMInstrInfo.td
@@ -5284,8 +5284,8 @@ let usesCustomInserter = 1, Uses = [R4], Defs = [R4, SP] in
 def win__dbzchk : SDNode<"ARMISD::WIN__DBZCHK", SDT_WIN__DBZCHK,
                          [SDNPHasChain, SDNPSideEffect, SDNPOutGlue]>;
 let usesCustomInserter = 1, Defs = [CPSR] in
-  def WIN__DBZCHK : PseudoInst<(outs), (ins GPR:$divisor), NoItinerary,
-                               [(win__dbzchk GPR:$divisor)]>;
+  def WIN__DBZCHK : PseudoInst<(outs), (ins tGPR:$divisor), NoItinerary,
+                               [(win__dbzchk tGPR:$divisor)]>;
 
 //===----------------------------------------------------------------------===//
 // TLS Instructions
diff --git a/llvm/test/CodeGen/ARM/Windows/dbzchk.ll b/llvm/test/CodeGen/ARM/Windows/dbzchk.ll
index 9019545..bb25527 100644
--- a/llvm/test/CodeGen/ARM/Windows/dbzchk.ll
+++ b/llvm/test/CodeGen/ARM/Windows/dbzchk.ll
@@ -142,3 +142,50 @@ attributes #0 = { optsize }
 ; CHECK-CFG: bl __rt_udiv
 ; CHECK-CFG: pop.w {{{.*}}, r11, pc}
 
+; RUN: llc -O0 -mtriple thumbv7--windows-itanium -filetype asm -o - %s | FileCheck %s -check-prefix CHECK-WIN__DBZCHK
+
+; long k(void);
+; int l(void);
+; int j(int i) {
+;   if (l() == -1)
+;     return 0;
+;   return k() % i;
+; }
+
+declare arm_aapcs_vfpcc i32 @k()
+declare arm_aapcs_vfpcc i32 @l()
+
+define arm_aapcs_vfpcc i32 @j(i32 %i) {
+entry:
+  %retval = alloca i32, align 4
+  %i.addr = alloca i32, align 4
+  store i32 %i, i32* %i.addr, align 4
+  %call = call arm_aapcs_vfpcc i32 @l()
+  %cmp = icmp eq i32 %call, -1
+  br i1 %cmp, label %if.then, label %if.end
+
+if.then:
+  store i32 0, i32* %retval, align 4
+  br label %return
+
+if.end:
+  %call1 = call arm_aapcs_vfpcc i32 @k()
+  %0 = load i32, i32* %i.addr, align 4
+  %rem = srem i32 %call1, %0
+  store i32 %rem, i32* %retval, align 4
+  br label %return
+
+return:
+  %1 = load i32, i32* %retval, align 4
+  ret i32 %1
+}
+
+; CHECK-WIN__DBZCHK-LABEL: j:
+; CHECK-WIN__DBZCHK: cbz r{{[0-7]}}, .LBB
+; CHECK-WIN__DBZCHK-NOT: cbz r8, .LBB
+; CHECK-WIN__DBZCHK-NOT: cbz r9, .LBB
+; CHECK-WIN__DBZCHK-NOT: cbz r10, .LBB
+; CHECK-WIN__DBZCHK-NOT: cbz r11, .LBB
+; CHECK-WIN__DBZCHK-NOT: cbz ip, .LBB
+; CHECK-WIN__DBZCHK-NOT: cbz lr, .LBB
+
-- 
2.7.4