[ARM] Enable spilling of the hGPR register class in Thumb2

Generalize code in Thumb2InstrInfo::storeRegToStackSlot() and
loadRegToStackSlot() to allow the GPR class or any of its sub-classes
(including hGPR) to be stored/loaded by ARM::t2STRi12/ARM::t2LDRi12.

Differential Revision: https://reviews.llvm.org/D51927

llvm-svn: 346401

1 files changed, 50 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/Thumb2/high-reg-spill.mir b/llvm/test/CodeGen/Thumb2/high-reg-spill.mir
new file mode 100644
index 00000000000..d9bfdcafa38
--- /dev/null
+++ b/llvm/test/CodeGen/Thumb2/high-reg-spill.mir
@@ -0,0 +1,50 @@
+# RUN: llc -run-pass regallocfast %s -o - | FileCheck %s
+
+# This test examines register allocation and spilling with Fast Register
+# Allocator. The test uses inline assembler that requests an input variable to
+# be loaded in a high register but at the same time has r12 marked as clobbered.
+# The allocator initially satisfies the load request by selecting r12 but then
+# needs to spill this register when it reaches the INLINEASM instruction and
+# notices its clobber definition.
+#
+# The test checks that the compiler is able to spill a register from the hGPR
+# class in Thumb2 by inserting the t2STRi12/t2LDRi12 instructions.
+
+--- |
+  ; ModuleID = 'test.ll'
+  source_filename = "test.c"
+  target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
+  target triple = "thumbv7m-none-unknown-eabi"
+
+  define dso_local void @constraint_h() {
+  entry:
+    %i = alloca i32, align 4
+    %0 = load i32, i32* %i, align 4
+    call void asm sideeffect "@ $0", "h,~{r12}"(i32 %0)
+    ret void
+  }
+
+...
+---
+name:            constraint_h
+tracksRegLiveness: true
+registers:
+  - { id: 0, class: hgpr }
+  - { id: 1, class: tgpr }
+stack:
+  - { id: 0, name: i, size: 4, alignment: 4, stack-id: 0, local-offset: -4 }
+body:             |
+  bb.0.entry:
+    %1:tgpr = tLDRspi %stack.0.i, 0, 14, $noreg :: (dereferenceable load 4 from %ir.i)
+    %0:hgpr = COPY %1
+    INLINEASM &"@ $0", 1, 589833, %0, 12, implicit-def early-clobber $r12
+    tBX_RET 14, $noreg
+
+...
+# CHECK: bb.0.entry:
+# CHECK-NEXT: renamable $r0 = tLDRspi %stack.0.i, 0, 14, $noreg :: (dereferenceable load 4 from %ir.i)
+# CHECK-NEXT: renamable $r12 = COPY killed renamable $r0
+# CHECK-NEXT: t2STRi12 killed $r12, %stack.1, 0, 14, $noreg :: (store 4 into %stack.1)
+# CHECK-NEXT: $r8 = t2LDRi12 %stack.1, 0, 14, $noreg :: (load 4 from %stack.1)
+# CHECK-NEXT: INLINEASM &"@ $0", 1, 589833, killed renamable $r8, 12, implicit-def early-clobber $r12
+# CHECK-NEXT: tBX_RET 14, $noreg