Support unaligned load/store on more ARM targets

This patch matches GCC behavior: the code used to only allow unaligned
load/store on ARM for v6+ Darwin, it will now allow unaligned load/store
for v6+ Darwin as well as for v7+ on Linux and NaCl.

The distinction is made because v6 doesn't guarantee support (but LLVM
assumes that Apple controls hardware+kernel and therefore have
conformant v6 CPUs), whereas v7 does provide this guarantee (and
Linux/NaCl behave sanely).

The patch keeps the -arm-strict-align command line option, and adds
-arm-no-strict-align. They behave similarly to GCC's -mstrict-align and
-mnostrict-align.

I originally encountered this discrepancy in FastIsel tests which expect
unaligned load/store generation. Overall this should slightly improve
performance in most cases because of reduced I$ pressure.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182175 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 144 insertions, 0 deletions

diff --git a/test/CodeGen/ARM/fast-isel-align.ll b/test/CodeGen/ARM/fast-isel-align.ll
new file mode 100644
index 0000000000..4e28a10cd1
--- /dev/null
+++ b/test/CodeGen/ARM/fast-isel-align.ll
@@ -0,0 +1,144 @@
+; RUN: llc < %s -O0 -fast-isel-abort -relocation-model=dynamic-no-pic -mtriple=armv7-apple-ios | FileCheck %s --check-prefix=ARM
+; RUN: llc < %s -O0 -fast-isel-abort -relocation-model=dynamic-no-pic -mtriple=thumbv7-apple-ios | FileCheck %s --check-prefix=THUMB
+; RUN: llc < %s -O0 -arm-strict-align -relocation-model=dynamic-no-pic -mtriple=armv7-apple-ios | FileCheck %s --check-prefix=ARM-STRICT-ALIGN
+; RUN: llc < %s -O0 -arm-strict-align -relocation-model=dynamic-no-pic -mtriple=thumbv7-apple-ios | FileCheck %s --check-prefix=THUMB-STRICT-ALIGN
+
+; RUN: llc < %s -O0 -fast-isel-abort -relocation-model=dynamic-no-pic -mtriple=armv7-linux-gnueabi | FileCheck %s --check-prefix=ARM
+; RUN: llc < %s -O0 -fast-isel-abort -relocation-model=dynamic-no-pic -mtriple=thumbv7-linux-gnueabi | FileCheck %s --check-prefix=THUMB
+; RUN: llc < %s -O0 -arm-strict-align -relocation-model=dynamic-no-pic -mtriple=armv7-linux-gnueabi | FileCheck %s --check-prefix=ARM-STRICT-ALIGN
+; RUN: llc < %s -O0 -arm-strict-align -relocation-model=dynamic-no-pic -mtriple=thumbv7-linux-gnueabi | FileCheck %s --check-prefix=THUMB-STRICT-ALIGN
+
+; RUN: llc < %s -O0 -fast-isel-abort -relocation-model=dynamic-no-pic -mtriple=armv7-unknown-nacl | FileCheck %s --check-prefix=ARM
+; RUN: llc < %s -O0 -arm-strict-align -relocation-model=dynamic-no-pic -mtriple=armv7-unknown-nacl | FileCheck %s --check-prefix=ARM-STRICT-ALIGN
+
+; RUN: llc < %s -O0  -fast-isel-abort -relocation-model=dynamic-no-pic -mtriple=armv7-unknown-unknown | FileCheck %s --check-prefix=ARM-STRICT-ALIGN
+; RUN: llc < %s -O0  -fast-isel-abort -relocation-model=dynamic-no-pic -mtriple=thumbv7-unknown-unknown | FileCheck %s --check-prefix=THUMB-STRICT-ALIGN
+; RUN: llc < %s -O0 -arm-no-strict-align -fast-isel-abort -relocation-model=dynamic-no-pic -mtriple=armv7-unknown-unknown | FileCheck %s --check-prefix=ARM
+; RUN: llc < %s -O0 -arm-no-strict-align -fast-isel-abort -relocation-model=dynamic-no-pic -mtriple=thumbv7-unknown-unknown | FileCheck %s --check-prefix=THUMB
+; RUN: llc < %s -O0 -relocation-model=dynamic-no-pic -mtriple=armv7-unknown-unknown | FileCheck %s --check-prefix=ARM-STRICT-ALIGN
+; RUN: llc < %s -O0 -relocation-model=dynamic-no-pic -mtriple=thumbv7-unknown-unknown | FileCheck %s --check-prefix=THUMB-STRICT-ALIGN
+
+; Check unaligned stores
+%struct.anon = type <{ float }>
+
+@a = common global %struct.anon* null, align 4
+
+define void @unaligned_store(float %x, float %y) nounwind {
+entry:
+; ARM: @unaligned_store
+; ARM: vmov r1, s0
+; ARM: str r1, [r0]
+
+; THUMB: @unaligned_store
+; THUMB: vmov r1, s0
+; THUMB: str r1, [r0]
+
+  %add = fadd float %x, %y
+  %0 = load %struct.anon** @a, align 4
+  %x1 = getelementptr inbounds %struct.anon* %0, i32 0, i32 0
+  store float %add, float* %x1, align 1
+  ret void
+}
+
+; Doublewords require only word-alignment.
+; rdar://10528060
+%struct.anon.0 = type { double }
+
+@foo_unpacked = common global %struct.anon.0 zeroinitializer, align 4
+
+define void @word_aligned_f64_store(double %a, double %b) nounwind {
+entry:
+; ARM: @word_aligned_f64_store
+; THUMB: @word_aligned_f64_store
+  %add = fadd double %a, %b
+  store double %add, double* getelementptr inbounds (%struct.anon.0* @foo_unpacked, i32 0, i32 0), align 4
+; ARM: vstr d16, [r0]
+; THUMB: vstr d16, [r0]
+  ret void
+}
+
+; Check unaligned loads of floats
+%class.TAlignTest = type <{ i16, float }>
+
+define zeroext i1 @unaligned_f32_load(%class.TAlignTest* %this) nounwind align 2 {
+entry:
+; ARM: @unaligned_f32_load
+; THUMB: @unaligned_f32_load
+  %0 = alloca %class.TAlignTest*, align 4
+  store %class.TAlignTest* %this, %class.TAlignTest** %0, align 4
+  %1 = load %class.TAlignTest** %0
+  %2 = getelementptr inbounds %class.TAlignTest* %1, i32 0, i32 1
+  %3 = load float* %2, align 1
+  %4 = fcmp une float %3, 0.000000e+00
+; ARM: ldr r[[R:[0-9]+]], [r0, #2]
+; ARM: vmov s0, r[[R]]
+; ARM: vcmpe.f32 s0, #0
+; THUMB: ldr.w r[[R:[0-9]+]], [r0, #2]
+; THUMB: vmov s0, r[[R]]
+; THUMB: vcmpe.f32 s0, #0
+  ret i1 %4
+}
+
+define void @unaligned_i16_store(i16 %x, i16* %y) nounwind {
+entry:
+; ARM-STRICT-ALIGN: @unaligned_i16_store
+; ARM-STRICT-ALIGN: strb
+; ARM-STRICT-ALIGN: strb
+
+; THUMB-STRICT-ALIGN: @unaligned_i16_store
+; THUMB-STRICT-ALIGN: strb
+; THUMB-STRICT-ALIGN: strb
+
+  store i16 %x, i16* %y, align 1
+  ret void
+}
+
+define i16 @unaligned_i16_load(i16* %x) nounwind {
+entry:
+; ARM-STRICT-ALIGN: @unaligned_i16_load
+; ARM-STRICT-ALIGN: ldrb
+; ARM-STRICT-ALIGN: ldrb
+
+; THUMB-STRICT-ALIGN: @unaligned_i16_load
+; THUMB-STRICT-ALIGN: ldrb
+; THUMB-STRICT-ALIGN: ldrb
+
+  %0 = load i16* %x, align 1
+  ret i16 %0
+}
+
+define void @unaligned_i32_store(i32 %x, i32* %y) nounwind {
+entry:
+; ARM-STRICT-ALIGN: @unaligned_i32_store
+; ARM-STRICT-ALIGN: strb
+; ARM-STRICT-ALIGN: strb
+; ARM-STRICT-ALIGN: strb
+; ARM-STRICT-ALIGN: strb
+
+; THUMB-STRICT-ALIGN: @unaligned_i32_store
+; THUMB-STRICT-ALIGN: strb
+; THUMB-STRICT-ALIGN: strb
+; THUMB-STRICT-ALIGN: strb
+; THUMB-STRICT-ALIGN: strb
+
+  store i32 %x, i32* %y, align 1
+  ret void
+}
+
+define i32 @unaligned_i32_load(i32* %x) nounwind {
+entry:
+; ARM-STRICT-ALIGN: @unaligned_i32_load
+; ARM-STRICT-ALIGN: ldrb
+; ARM-STRICT-ALIGN: ldrb
+; ARM-STRICT-ALIGN: ldrb
+; ARM-STRICT-ALIGN: ldrb
+
+; THUMB-STRICT-ALIGN: @unaligned_i32_load
+; THUMB-STRICT-ALIGN: ldrb
+; THUMB-STRICT-ALIGN: ldrb
+; THUMB-STRICT-ALIGN: ldrb
+; THUMB-STRICT-ALIGN: ldrb
+
+  %0 = load i32* %x, align 1
+  ret i32 %0
+}