[ARM] GlobalISel: Support ROPI global variables

In the ROPI relocation model, read-only variables are accessed relative
to the PC. We use the (MOV|LDRLIT)_ga_pcrel pseudoinstructions for this.

llvm-svn: 312323

3 files changed, 198 insertions, 3 deletions

diff --git a/llvm/test/CodeGen/ARM/GlobalISel/arm-isel-globals-ropi-rwpi.ll b/llvm/test/CodeGen/ARM/GlobalISel/arm-isel-globals-ropi-rwpi.ll
new file mode 100644
index 00000000000..2616540003d
--- /dev/null
+++ b/llvm/test/CodeGen/ARM/GlobalISel/arm-isel-globals-ropi-rwpi.ll
@@ -0,0 +1,76 @@
+; RUN: llc -mtriple armv7-linux -relocation-model=ropi -mattr=-no-movt,+v8m -global-isel %s -o - | FileCheck %s -check-prefixes=CHECK,RW-DEFAULT-MOVT,RW-DEFAULT,ROPI-MOVT,ROPI
+; RUN: llc -mtriple armv7-linux -relocation-model=ropi -mattr=+no-movt -global-isel %s -o - | FileCheck %s -check-prefixes=CHECK,RW-DEFAULT-NOMOVT,RW-DEFAULT,ROPI-NOMOVT,ROPI
+
+@internal_global = internal global i32 42
+define i32 @test_internal_global() {
+; CHECK-LABEL: test_internal_global:
+; RW-DEFAULT-MOVT: movw r[[ADDR:[0-9]+]], :lower16:internal_global
+; RW-DEFAULT-MOVT-NEXT: movt r[[ADDR]], :upper16:internal_global
+; RW-DEFAULT-NOMOVT: ldr r[[ADDR:[0-9]+]], [[LABEL:.L[[:alnum:]_]+]]
+; RW-DEFAULT-NEXT: ldr r0, [r[[ADDR]]]
+; RW-DEFAULT-NEXT: bx lr
+; RW-DEFAULT-NOMOVT: [[LABEL]]:
+; RW-DEFAULT-NOMOVT-NEXT: .long internal_global
+entry:
+  %v = load i32, i32* @internal_global
+  ret i32 %v
+}
+
+@external_global = external global i32
+define i32 @test_external_global() {
+; CHECK-LABEL: test_external_global:
+; RW-DEFAULT-MOVT: movw r[[ADDR:[0-9]+]], :lower16:external_global
+; RW-DEFAULT-MOVT-NEXT: movt r[[ADDR]], :upper16:external_global
+; RW-DEFAULT-NOMOVT: ldr r[[ADDR:[0-9]+]], [[LABEL:.L[[:alnum:]_]+]]
+; RW-DEFAULT-NEXT: ldr r0, [r[[ADDR]]]
+; RW-DEFAULT-NEXT: bx lr
+; RW-DEFAULT-NOMOVT: [[LABEL]]:
+; RW-DEFAULT-NOMOVT: .long external_global
+entry:
+  %v = load i32, i32* @external_global
+  ret i32 %v
+}
+
+@internal_constant = internal constant i32 42
+define i32 @test_internal_constant() {
+; CHECK-LABEL: test_internal_constant:
+; ROPI-MOVT: movw [[OFFSET:r[0-9]+]], :lower16:(internal_constant-([[ANCHOR:.L[[:alnum:]_]+]]+8)
+; ROPI-MOVT-NEXT: movt [[OFFSET]], :upper16:(internal_constant-([[ANCHOR]]+8)
+; ROPI-MOVT-NEXT: [[ANCHOR]]:
+; ROPI-NOMOVT: ldr [[OFFSET:r[0-9]+]], [[LABEL:.L[[:alnum:]_]+]]
+; ROPI-NOMOVT-NEXT: [[ANCHOR:.L[[:alnum:]_]+]]:
+; ROPI-NEXT: add r[[ADDR:[0-9]+]], pc, [[OFFSET]]
+; ROPI-NEXT: ldr r0, [r[[ADDR]]]
+; ROPI-NEXT: bx lr
+; ROPI-NOMOVT: [[LABEL]]:
+; ROPI-NOMOVT-NEXT: .long internal_constant-([[ANCHOR]]+8)
+entry:
+  %v = load i32, i32* @internal_constant
+  ret i32 %v
+}
+
+@external_constant = external constant i32
+define i32 @test_external_constant() {
+; CHECK-LABEL: test_external_constant:
+; ROPI-MOVT: movw [[OFFSET:r[0-9]+]], :lower16:(external_constant-([[ANCHOR:.L[[:alnum:]_]+]]+8)
+; ROPI-MOVT-NEXT: movt [[OFFSET]], :upper16:(external_constant-([[ANCHOR]]+8)
+; ROPI-MOVT-NEXT: [[ANCHOR]]:
+; ROPI-NOMOVT: ldr [[OFFSET:r[0-9]+]], [[LABEL:.L[[:alnum:]_]+]]
+; ROPI-NOMOVT-NEXT: [[ANCHOR:.L[[:alnum:]_]+]]:
+; ROPI-NEXT: add r[[ADDR:[0-9]+]], pc, [[OFFSET]]
+; ROPI-NEXT: ldr r0, [r[[ADDR]]]
+; ROPI-NEXT: bx lr
+; ROPI-NOMOVT: [[LABEL]]:
+; ROPI-NOMOVT-NEXT: .long external_constant-([[ANCHOR]]+8)
+entry:
+  %v = load i32, i32* @external_constant
+  ret i32 %v
+}
+
+; RW-DEFAULT-NOMOVT: internal_global:
+; RW-DEFAULT-NOMOVT: .long 42
+; RW-DEFAULT-NOMOVT: .size internal_global, 4
+
+; ROPI-NOMOVT: internal_constant:
+; ROPI-NOMOVT: .long 42
+; ROPI-NOMOVT: .size internal_constant, 4
diff --git a/llvm/test/CodeGen/ARM/GlobalISel/arm-select-globals-ropi-rwpi.mir b/llvm/test/CodeGen/ARM/GlobalISel/arm-select-globals-ropi-rwpi.mir
new file mode 100644
index 00000000000..fc8d3bc4152
--- /dev/null
+++ b/llvm/test/CodeGen/ARM/GlobalISel/arm-select-globals-ropi-rwpi.mir
@@ -0,0 +1,121 @@
+# RUN: llc -O0 -mtriple arm-linux -relocation-model=ropi -mattr=-no-movt,+v8m -global-isel -run-pass=instruction-select -verify-machineinstrs %s -o - | FileCheck %s -check-prefixes=CHECK,RW-DEFAULT-MOVT,RW-DEFAULT,ROPI-MOVT,ROPI
+# RUN: llc -O0 -mtriple arm-linux -relocation-model=ropi -mattr=+no-movt -global-isel -run-pass=instruction-select -verify-machineinstrs %s -o - | FileCheck %s -check-prefixes=CHECK,RW-DEFAULT-NOMOVT,RW-DEFAULT,ROPI-NOMOVT,ROPI
+--- |
+  @internal_global = internal global i32 42
+  define void @test_internal_global() { ret void }
+
+  @external_global = external global i32
+  define void @test_external_global() { ret void }
+
+  @internal_constant = internal constant i32 42
+  define void @test_internal_constant() { ret void }
+
+  @external_constant = external constant i32
+  define void @test_external_constant() { ret void }
+...
+---
+name:            test_internal_global
+# CHECK-LABEL: name: test_internal_global
+legalized:       true
+regBankSelected: true
+selected:        false
+# CHECK: selected: true
+registers:
+  - { id: 0, class: gprb }
+  - { id: 1, class: gprb }
+# RW-DEFAULT-NOMOVT: constants:
+# RW-DEFAULT-NOMOVT: id: 0
+# RW-DEFAULT-NOMOVT: value: 'i32* @internal_global'
+body:             |
+  bb.0:
+    %0(p0) = G_GLOBAL_VALUE @internal_global
+    ; RW-DEFAULT-MOVT: [[G:%[0-9]+]] = MOVi32imm @internal_global
+    ; RW-DEFAULT-NOMOVT: [[G:%[0-9]+]] = LDRi12 %const.0, 0, 14, _ :: (load 4 from constant-pool)
+
+    %1(s32) = G_LOAD %0(p0) :: (load 4 from @internal_global)
+    ; CHECK: [[V:%[0-9]+]] = LDRi12 [[G]], 0, 14, _ :: (load 4 from @internal_global)
+
+    %r0 = COPY %1(s32)
+    ; CHECK: %r0 = COPY [[V]]
+
+    BX_RET 14, _, implicit %r0
+    ; CHECK: BX_RET 14, _, implicit %r0
+...
+---
+name:            test_external_global
+# CHECK-LABEL: name: test_external_global
+legalized:       true
+regBankSelected: true
+selected:        false
+# CHECK: selected: true
+registers:
+  - { id: 0, class: gprb }
+  - { id: 1, class: gprb }
+# RW-DEFAULT-NOMOVT: constants:
+# RW-DEFAULT-NOMOVT: id: 0
+# RW-DEFAULT-NOMOVT: value: 'i32* @external_global'
+body:             |
+  bb.0:
+    %0(p0) = G_GLOBAL_VALUE @external_global
+    ; RW-DEFAULT-MOVT: [[G:%[0-9]+]] = MOVi32imm @external_global
+    ; RW-DEFAULT-NOMOVT: [[G:%[0-9]+]] = LDRi12 %const.0, 0, 14, _ :: (load 4 from constant-pool)
+
+    %1(s32) = G_LOAD %0(p0) :: (load 4 from @external_global)
+    ; CHECK: [[V:%[0-9]+]] = LDRi12 [[G]], 0, 14, _ :: (load 4 from @external_global)
+
+    %r0 = COPY %1(s32)
+    ; CHECK: %r0 = COPY [[V]]
+
+    BX_RET 14, _, implicit %r0
+    ; CHECK: BX_RET 14, _, implicit %r0
+...
+---
+name:            test_internal_constant
+# CHECK-LABEL: name: test_internal_constant
+legalized:       true
+regBankSelected: true
+selected:        false
+# CHECK: selected: true
+registers:
+  - { id: 0, class: gprb }
+  - { id: 1, class: gprb }
+body:             |
+  bb.0:
+    %0(p0) = G_GLOBAL_VALUE @internal_constant
+    ; ROPI-MOVT: [[G:%[0-9]+]] = MOV_ga_pcrel @internal_constant
+    ; ROPI-NOMOVT: [[G:%[0-9]+]] = LDRLIT_ga_pcrel @internal_constant
+
+    %1(s32) = G_LOAD %0(p0) :: (load 4 from @internal_constant)
+    ; CHECK: [[V:%[0-9]+]] = LDRi12 [[G]], 0, 14, _ :: (load 4 from @internal_constant)
+
+    %r0 = COPY %1(s32)
+    ; CHECK: %r0 = COPY [[V]]
+
+    BX_RET 14, _, implicit %r0
+    ; CHECK: BX_RET 14, _, implicit %r0
+...
+---
+name:            test_external_constant
+# CHECK-LABEL: name: test_external_constant
+legalized:       true
+regBankSelected: true
+selected:        false
+# CHECK: selected: true
+registers:
+  - { id: 0, class: gprb }
+  - { id: 1, class: gprb }
+body:             |
+  bb.0:
+    %0(p0) = G_GLOBAL_VALUE @external_constant
+    ; ROPI-MOVT: [[G:%[0-9]+]] = MOV_ga_pcrel @external_constant
+    ; ROPI-NOMOVT: [[G:%[0-9]+]] = LDRLIT_ga_pcrel @external_constant
+
+    %1(s32) = G_LOAD %0(p0) :: (load 4 from @external_constant)
+    ; CHECK: [[V:%[0-9]+]] = LDRi12 [[G]], 0, 14, _ :: (load 4 from @external_constant)
+
+    %r0 = COPY %1(s32)
+    ; CHECK: %r0 = COPY [[V]]
+
+    BX_RET 14, _, implicit %r0
+    ; CHECK: BX_RET 14, _, implicit %r0
+...
diff --git a/llvm/test/CodeGen/ARM/GlobalISel/arm-unsupported.ll b/llvm/test/CodeGen/ARM/GlobalISel/arm-unsupported.ll
index 9d09fe0dda1..19ccc1773e3 100644
--- a/llvm/test/CodeGen/ARM/GlobalISel/arm-unsupported.ll
+++ b/llvm/test/CodeGen/ARM/GlobalISel/arm-unsupported.ll
@@ -116,9 +116,7 @@ define i32 @test_thread_local_global() {
 @a_global = external global i32
 
 define i32 @test_global_reloc_models() {
-; This is only unsupported for the PIC, ROPI, RWPI relocation modes.
-; ROPI: remark: {{.*}} cannot select: {{.*}} G_GLOBAL_VALUE
-; ROPI-LABEL: warning: Instruction selection used fallback path for test_global_reloc_models
+; This is only unsupported for the RWPI relocation modes.
 ; RWPI: remark: {{.*}} cannot select: {{.*}} G_GLOBAL_VALUE
 ; RWPI-LABEL: warning: Instruction selection used fallback path for test_global_reloc_models
 ; ROPI-RWPI: remark: {{.*}} cannot select: {{.*}} G_GLOBAL_VALUE