Fix frame pointer loads/stores in the ARM integrated assembler.

tests_lit/assembler/arm32/store-sf.ll

+; Sample program that generates "str reg, [fp, #CCCC]", to show that we
+; recognize that "fp" should be used instead of "sp".
+
+; REQUIRES: allow_dump
+
+; Compile using standalone assembler.
+; RUN: %p2i --filetype=asm -i %s --target=arm32 --args -Om1 \
+; RUN:   | FileCheck %s --check-prefix=ASM
+
+; Show bytes in assembled standalone code.
+; RUN: %p2i --filetype=asm -i %s --target=arm32 --assemble --disassemble \
+; RUN:   --args -Om1 | FileCheck %s --check-prefix=DIS
+
+; Compile using integrated assembler.
+; RUN: %p2i --filetype=iasm -i %s --target=arm32 --args -Om1 \
+; RUN:   -unsafe-ias | FileCheck %s --check-prefix=IASM
+
+; Show bytes in assembled integrated code.
+; RUN: %p2i --filetype=iasm -i %s --target=arm32 --assemble --disassemble \
+; RUN:   --args -Om1 -unsafe-ias | FileCheck %s --check-prefix=DIS
+
+define internal void @test_vla_in_loop(i32 %n) {
+; ASM-LABEL: test_vla_in_loop:
+; DIS-LABEL: 00000000 <test_vla_in_loop>:
+; IASM-LABEL: test_vla_in_loop:
+
+entry:
+
+; ASM-NEXT: .Ltest_vla_in_loop$entry:
+; IASM-NEXT: .Ltest_vla_in_loop$entry:
+
+; ASM-NEXT:     push    {fp}
+; DIS-NEXT:    0:       e52db004
+; IASM-NEXT:    .byte 0x4
+; IASM-NEXT:    .byte 0xb0
+; IASM-NEXT:    .byte 0x2d
+; IASM-NEXT:    .byte 0xe5
+
+; ASM-NEXT:     mov     fp, sp
+; DIS-NEXT:    4:       e1a0b00d
+; IASM-NEXT:    .byte 0xd
+; IASM-NEXT:    .byte 0xb0
+; IASM-NEXT:    .byte 0xa0
+; IASM-NEXT:    .byte 0xe1
+
+; ASM-NEXT:     sub     sp, sp, #12
+; DIS-NEXT:    8:       e24dd00c
+; IASM-NEXT:    .byte 0xc
+; IASM-NEXT:    .byte 0xd0
+; IASM-NEXT:    .byte 0x4d
+; IASM-NEXT:    .byte 0xe2
+
+; **** Example of fixed instruction.
+; ASM-NEXT:     str     r0, [fp, #-4]
+; DIS-NEXT:    c:       e50b0004
+; IASM-NEXT:    .byte 0x4
+; IASM-NEXT:    .byte 0x0
+; IASM-NEXT:    .byte 0xb
+; IASM-NEXT:    .byte 0xe5
+
+  br label %next
+
+; ASM-NEXT:     b       .Ltest_vla_in_loop$next
+; DIS-NEXT:   10:       eaffffff
+
+; IASM-NEXT:    .byte 0xff
+; IASM-NEXT:    .byte 0xff
+; IASM-NEXT:    .byte 0xff
+; IASM-NEXT:    .byte 0xea

[Karl, 2015/11/11 23:38:38]

Added following comment.

+
+; Put the variable-length alloca in a non-entry block, to reduce the
+; chance the optimizer putting it before the regular frame creation.
+
+next:
+  %v = alloca i8, i32 %n, align 4
+  ret void
+}