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llvm-mirror/test/CodeGen/Thumb/frame-access.ll
Eli Friedman 1cc9a9a285 [ARM] Don't reserve R12 on Thumb1 as an emergency spill slot. 
The current implementation of ThumbRegisterInfo::saveScavengerRegister
is bad for two reasons: one, it's buggy, and two, it blocks using R12
for other optimizations.  So this patch gets rid of it, and adds the
necessary support for using an ordinary emergency spill slot on Thumb1.

(Specifically, I think saveScavengerRegister was broken by r305625, and
nobody noticed for two years because the codepath is almost never used.
The new code will also probably not be used much, but it now has better
tests, and if we fail to emit a necessary emergency spill slot we get a
reasonable error message instead of a miscompile.)

A rough outline of the changes in the patch:

1. Gets rid of ThumbRegisterInfo::saveScavengerRegister.
2. Modifies ARMFrameLowering::determineCalleeSaves to allocate an
emergency spill slot for Thumb1.
3. Implements useFPForScavengingIndex, so the emergency spill slot isn't
placed at a negative offset from FP on Thumb1.
4. Modifies the heuristics for allocating an emergency spill slot to
support Thumb1.  This includes fixing ExtraCSSpill so we don't try to
use "lr" as a substitute for allocating an emergency spill slot.
5. Allocates a base pointer in more cases, so the emergency spill slot
is always accessible.
6. Modifies ARMFrameLowering::ResolveFrameIndexReference to compute the
right offset in the new cases where we're forcing a base pointer.
7. Ensures we never generate a load or store with an offset outside of
its frame object.  This makes the heuristics more straightforward.
8. Changes Thumb1 prologue and epilogue emission so it never uses
register scavenging.

Some of the changes to the emergency spill slot heuristics in
determineCalleeSaves affect ARM/Thumb2; hopefully, they should allow
the compiler to avoid allocating an emergency spill slot in cases
where it isn't necessary. The rest of the changes should only affect
Thumb1.

Differential Revision: https://reviews.llvm.org/D63677

llvm-svn: 364490
2019-06-26 23:46:51 +00:00

419 lines
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LLVM
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; RUN: llc -mtriple=thumbv6m-eabi -frame-pointer=none %s -o - | FileCheck %s
; struct S { int x[128]; } s;
; int f(int *, int, int, int, struct S);
; int g(int *, int, int, int, int, int);
; int h(int *, int *, int *);
; int u(int *, int *, int *, struct S, struct S);
%struct.S = type { [128 x i32] }
%struct.__va_list = type { i8* }
@s = common dso_local global %struct.S zeroinitializer, align 4
declare void @llvm.va_start(i8*)
declare dso_local i32 @g(i32*, i32, i32, i32, i32, i32) local_unnamed_addr
declare dso_local i32 @f(i32*, i32, i32, i32, %struct.S* byval align 4) local_unnamed_addr
declare dso_local i32 @h(i32*, i32*, i32*) local_unnamed_addr
declare dso_local i32 @u(i32*, i32*, i32*, %struct.S* byval align 4, %struct.S* byval align 4) local_unnamed_addr
;
; Test access to arguments, passed on stack (including varargs)
;
; Usual case, access via SP
; int test_args_sp(int a, int b, int c, int d, int e) {
; int v[4];
; return g(v, a, b, c, d, e);
; }
define dso_local i32 @test_args_sp(i32 %a, i32 %b, i32 %c, i32 %d, i32 %e) local_unnamed_addr {
entry:
%v = alloca [4 x i32], align 4
%0 = bitcast [4 x i32]* %v to i8*
%arraydecay = getelementptr inbounds [4 x i32], [4 x i32]* %v, i32 0, i32 0
%call = call i32 @g(i32* nonnull %arraydecay, i32 %a, i32 %b, i32 %c, i32 %d, i32 %e)
ret i32 %call
}
; CHECK-LABEL: test_args_sp
; Load `e`
; CHECK: ldr r0, [sp, #32]
; CHECK-NEXT: str r3, [sp]
; Pass `e` on stack
; CHECK-NEXT: str r0, [sp, #4]
; CHECK: bl g
; int test_varargs_sp(int a, ...) {
; int v[4];
; __builtin_va_list ap;
; __builtin_va_start(ap, a);
; return g(v, a, 0, 0, 0, 0);
; }
define dso_local i32 @test_varargs_sp(i32 %a, ...) local_unnamed_addr {
entry:
%v = alloca [4 x i32], align 4
%ap = alloca %struct.__va_list, align 4
%0 = bitcast [4 x i32]* %v to i8*
%1 = bitcast %struct.__va_list* %ap to i8*
call void @llvm.va_start(i8* nonnull %1)
%arraydecay = getelementptr inbounds [4 x i32], [4 x i32]* %v, i32 0, i32 0
%call = call i32 @g(i32* nonnull %arraydecay, i32 %a, i32 0, i32 0, i32 0, i32 0)
ret i32 %call
}
; CHECK-LABEL: test_varargs_sp
; Three incoming varargs in registers
; CHECK: sub sp, #12
; CHECK: sub sp, #28
; Incoming arguments area is accessed via SP
; CHECK: add r0, sp, #36
; CHECK: stm r0!, {r1, r2, r3}
; Re-aligned stack, access via FP
; int test_args_realign(int a, int b, int c, int d, int e) {
; __attribute__((aligned(16))) int v[4];
; return g(v, a, b, c, d, e);
; }
; Function Attrs: nounwind
define dso_local i32 @test_args_realign(i32 %a, i32 %b, i32 %c, i32 %d, i32 %e) local_unnamed_addr {
entry:
%v = alloca [4 x i32], align 16
%0 = bitcast [4 x i32]* %v to i8*
%arraydecay = getelementptr inbounds [4 x i32], [4 x i32]* %v, i32 0, i32 0
%call = call i32 @g(i32* nonnull %arraydecay, i32 %a, i32 %b, i32 %c, i32 %d, i32 %e)
ret i32 %call
}
; CHECK-LABEL: test_args_realign
; Setup frame pointer
; CHECK: add r7, sp, #8
; Align stack
; CHECK: mov r4, sp
; CHECK-NEXT: lsrs r4, r4, #4
; CHECK-NEXT: lsls r4, r4, #4
; CHECK-NEXT: mov sp, r4
; Load `e` via FP
; CHECK: ldr r0, [r7, #8]
; CHECK-NEXT: str r3, [sp]
; Pass `e` as argument
; CHECK-NEXT: str r0, [sp, #4]
; CHECK: bl g
; int test_varargs_realign(int a, ...) {
; __attribute__((aligned(16))) int v[4];
; __builtin_va_list ap;
; __builtin_va_start(ap, a);
; return g(v, a, 0, 0, 0, 0);
; }
define dso_local i32 @test_varargs_realign(i32 %a, ...) local_unnamed_addr {
entry:
%v = alloca [4 x i32], align 16
%ap = alloca %struct.__va_list, align 4
%0 = bitcast [4 x i32]* %v to i8*
%1 = bitcast %struct.__va_list* %ap to i8*
call void @llvm.va_start(i8* nonnull %1)
%arraydecay = getelementptr inbounds [4 x i32], [4 x i32]* %v, i32 0, i32 0
%call = call i32 @g(i32* nonnull %arraydecay, i32 %a, i32 0, i32 0, i32 0, i32 0)
ret i32 %call
}
; CHECK-LABEL: test_varargs_realign
; Three incoming register varargs
; CHECK: sub sp, #12
; Setup frame pointer
; CHECK: add r7, sp, #8
; Align stack
; CHECK: mov r4, sp
; CHECK-NEXT: lsrs r4, r4, #4
; CHECK-NEXT: lsls r4, r4, #4
; CHECK-NEXT: mov sp, r4
; Incoming register varargs stored via FP
; CHECK: mov r0, r7
; CHECK-NEXT: adds r0, #8
; CHECK-NEXT: stm r0!, {r1, r2, r3}
; VLAs present, access via FP
; int test_args_vla(int a, int b, int c, int d, int e) {
; int v[a];
; return g(v, a, b, c, d, e);
; }
define dso_local i32 @test_args_vla(i32 %a, i32 %b, i32 %c, i32 %d, i32 %e) local_unnamed_addr {
entry:
%vla = alloca i32, i32 %a, align 4
%call = call i32 @g(i32* nonnull %vla, i32 %a, i32 %b, i32 %c, i32 %d, i32 %e)
ret i32 %call
}
; CHECK-LABEL: test_args_vla
; Setup frame pointer
; CHECK: add r7, sp, #12
; Allocate outgoing stack arguments space
; CHECK: sub sp, #4
; Load `e` via FP
; CHECK: ldr r5, [r7, #8]
; Pass `d` and `e` as arguments
; CHECK-NEXT: str r3, [sp]
; CHECK-NEXT: str r5, [sp, #4]
; CHECK: bl g
; int test_varargs_vla(int a, ...) {
; int v[a];
; __builtin_va_list ap;
; __builtin_va_start(ap, a);
; return g(v, a, 0, 0, 0, 0);
; }
define dso_local i32 @test_varargs_vla(i32 %a, ...) local_unnamed_addr {
entry:
%ap = alloca %struct.__va_list, align 4
%vla = alloca i32, i32 %a, align 4
%0 = bitcast %struct.__va_list* %ap to i8*
call void @llvm.va_start(i8* nonnull %0)
%call = call i32 @g(i32* nonnull %vla, i32 %a, i32 0, i32 0, i32 0, i32 0)
ret i32 %call
}
; CHECK-LABEL: test_varargs_vla
; Three incoming register varargs
; CHECK: sub sp, #12
; Setup frame pointer
; CHECK: add r7, sp, #8
; Register varargs stored via FP
; CHECK-DAG: str r3, [r7, #16]
; CHECK-DAG: str r2, [r7, #12]
; CHECK-DAG: str r1, [r7, #8]
; Moving SP, access via SP
; int test_args_moving_sp(int a, int b, int c, int d, int e) {
; int v[4];
; return f(v, a, b + c + d, e, s) + h(v, v+1, v+2);
; }
define dso_local i32 @test_args_moving_sp(i32 %a, i32 %b, i32 %c, i32 %d, i32 %e) local_unnamed_addr {
entry:
%v = alloca [4 x i32], align 4
%0 = bitcast [4 x i32]* %v to i8*
%arraydecay = getelementptr inbounds [4 x i32], [4 x i32]* %v, i32 0, i32 0
%add = add nsw i32 %c, %b
%add1 = add nsw i32 %add, %d
%call = call i32 @f(i32* nonnull %arraydecay, i32 %a, i32 %add1, i32 %e, %struct.S* byval nonnull align 4 @s)
%add.ptr = getelementptr inbounds [4 x i32], [4 x i32]* %v, i32 0, i32 1
%add.ptr5 = getelementptr inbounds [4 x i32], [4 x i32]* %v, i32 0, i32 2
%call6 = call i32 @h(i32* nonnull %arraydecay, i32* nonnull %add.ptr, i32* nonnull %add.ptr5)
%add7 = add nsw i32 %call6, %call
ret i32 %add7
}
; CHECK-LABEL: test_args_moving_sp
; 20 bytes callee-saved area
; CHECK: push {r4, r5, r6, r7, lr}
; 20 bytes locals
; CHECK: sub sp, #20
; Setup base pointer
; CHECK: mov r6, sp
; Allocate outgoing arguments space
; CHECK: sub sp, #508
; CHECK: sub sp, #4
; Load `e` via BP, 40 = 20 + 20
; CHECK: ldr r3, [r6, #40]
; CHECK: bl f
; Stack restored before next call
; CHECK-NEXT: add sp, #508
; CHECK-NEXT: add sp, #4
; CHECK: bl h
; int test_varargs_moving_sp(int a, ...) {
; int v[4];
; __builtin_va_list ap;
; __builtin_va_start(ap, a);
; return f(v, a, 0, 0, s) + h(v, v+1, v+2);
; }
define dso_local i32 @test_varargs_moving_sp(i32 %a, ...) local_unnamed_addr {
entry:
%v = alloca [4 x i32], align 4
%ap = alloca %struct.__va_list, align 4
%0 = bitcast [4 x i32]* %v to i8*
%1 = bitcast %struct.__va_list* %ap to i8*
call void @llvm.va_start(i8* nonnull %1)
%arraydecay = getelementptr inbounds [4 x i32], [4 x i32]* %v, i32 0, i32 0
%call = call i32 @f(i32* nonnull %arraydecay, i32 %a, i32 0, i32 0, %struct.S* byval nonnull align 4 @s)
%add.ptr = getelementptr inbounds [4 x i32], [4 x i32]* %v, i32 0, i32 1
%add.ptr5 = getelementptr inbounds [4 x i32], [4 x i32]* %v, i32 0, i32 2
%call6 = call i32 @h(i32* nonnull %arraydecay, i32* nonnull %add.ptr, i32* nonnull %add.ptr5)
%add = add nsw i32 %call6, %call
ret i32 %add
}
; CHECK-LABEL: test_varargs_moving_sp
; Three incoming register varargs
; CHECK: sub sp, #12
; 16 bytes callee-saves
; CHECK: push {r4, r5, r6, lr}
; 20 bytes locals
; CHECK: sub sp, #20
; Incoming varargs stored via BP, 36 = 20 + 16
; CHECK: mov r0, r6
; CHECK-NEXT: adds r0, #36
; CHECK-NEXT: stm r0!, {r1, r2, r3}
;
; Access to locals
;
; Usual case, access via SP.
; int test_local(int n) {
; int v[4];
; int x, y, z;
; h(&x, &y, &z);
; return g(v, x, y, z, 0, 0);
; }
define dso_local i32 @test_local(i32 %n) local_unnamed_addr {
entry:
%v = alloca [4 x i32], align 4
%x = alloca i32, align 4
%y = alloca i32, align 4
%z = alloca i32, align 4
%0 = bitcast [4 x i32]* %v to i8*
%1 = bitcast i32* %x to i8*
%2 = bitcast i32* %y to i8*
%3 = bitcast i32* %z to i8*
%call = call i32 @h(i32* nonnull %x, i32* nonnull %y, i32* nonnull %z)
%arraydecay = getelementptr inbounds [4 x i32], [4 x i32]* %v, i32 0, i32 0
%4 = load i32, i32* %x, align 4
%5 = load i32, i32* %y, align 4
%6 = load i32, i32* %z, align 4
%call1 = call i32 @g(i32* nonnull %arraydecay, i32 %4, i32 %5, i32 %6, i32 0, i32 0)
ret i32 %call1
}
; CHECK-LABEL: test_local
; Arguments to `h` relative to SP
; CHECK: add r0, sp, #20
; CHECK-NEXT: add r1, sp, #16
; CHECK-NEXT: add r2, sp, #12
; CHECK-NEXT: bl h
; Load `x`, `y`, and `z` via SP
; CHECK: ldr r1, [sp, #20]
; CHECK-NEXT: ldr r2, [sp, #16]
; CHECK-NEXT: ldr r3, [sp, #12]
; CHECK: bl g
; Re-aligned stack, access via SP.
; int test_local_realign(int n) {
; __attribute__((aligned(16))) int v[4];
; int x, y, z;
; h(&x, &y, &z);
; return g(v, x, y, z, 0, 0);
; }
define dso_local i32 @test_local_realign(i32 %n) local_unnamed_addr {
entry:
%v = alloca [4 x i32], align 16
%x = alloca i32, align 4
%y = alloca i32, align 4
%z = alloca i32, align 4
%0 = bitcast [4 x i32]* %v to i8*
%1 = bitcast i32* %x to i8*
%2 = bitcast i32* %y to i8*
%3 = bitcast i32* %z to i8*
%call = call i32 @h(i32* nonnull %x, i32* nonnull %y, i32* nonnull %z)
%arraydecay = getelementptr inbounds [4 x i32], [4 x i32]* %v, i32 0, i32 0
%4 = load i32, i32* %x, align 4
%5 = load i32, i32* %y, align 4
%6 = load i32, i32* %z, align 4
%call1 = call i32 @g(i32* nonnull %arraydecay, i32 %4, i32 %5, i32 %6, i32 0, i32 0)
ret i32 %call1
}
; CHECK-LABEL: test_local_realign
; Setup frame pointer
; CHECK: add r7, sp, #8
; Re-align stack
; CHECK: mov r4, sp
; CHECK-NEXT: lsrs r4, r4, #4
; CHECK-NEXT: lsls r4, r4, #4
; CHECK-NEXT: mov sp, r4
; Arguments to `h` computed relative to SP
; CHECK: add r0, sp, #28
; CHECK-NEXT: add r1, sp, #24
; CHECK-NEXT: add r2, sp, #20
; CHECK-NEXT: bl h
; Load `x`, `y`, and `z` via SP for passing to `g`
; CHECK: ldr r1, [sp, #28]
; CHECK-NEXT: ldr r2, [sp, #24]
; CHECK-NEXT: ldr r3, [sp, #20]
; CHECK: bl g
; VLAs, access via BP.
; int test_local_vla(int n) {
; int v[n];
; int x, y, z;
; h(&x, &y, &z);
; return g(v, x, y, z, 0, 0);
; }
define dso_local i32 @test_local_vla(i32 %n) local_unnamed_addr {
entry:
%x = alloca i32, align 4
%y = alloca i32, align 4
%z = alloca i32, align 4
%vla = alloca i32, i32 %n, align 4
%0 = bitcast i32* %x to i8*
%1 = bitcast i32* %y to i8*
%2 = bitcast i32* %z to i8*
%call = call i32 @h(i32* nonnull %x, i32* nonnull %y, i32* nonnull %z)
%3 = load i32, i32* %x, align 4
%4 = load i32, i32* %y, align 4
%5 = load i32, i32* %z, align 4
%call1 = call i32 @g(i32* nonnull %vla, i32 %3, i32 %4, i32 %5, i32 0, i32 0)
ret i32 %call1
}
; CHECK-LABEL: test_local_vla
; Setup frame pointer
; CHECK: add r7, sp, #12
; Setup base pointer
; CHECK: mov r6, sp
; CHECK: mov r5, r6
; Arguments to `h` compute relative to BP
; CHECK: adds r0, r6, #7
; CHECK-NEXT: adds r0, #1
; CHECK-NEXT: adds r1, r6, #4
; CHECK-NEXT: mov r2, r6
; CHECK-NEXT: bl h
; Load `x`, `y`, `z` via BP (r5 should still have the value of r6 from the move
; above)
; CHECK: ldr r3, [r5]
; CHECK-NEXT: ldr r2, [r5, #4]
; CHECK-NEXT: ldr r1, [r5, #8]
; CHECK: bl g
; Moving SP, access via SP.
; int test_local_moving_sp(int n) {
; int v[4];
; int x, y, z;
; return u(v, &x, &y, s, s) + u(v, &y, &z, s, s);
; }
define dso_local i32 @test_local_moving_sp(i32 %n) local_unnamed_addr {
entry:
%v = alloca [4 x i32], align 4
%x = alloca i32, align 4
%y = alloca i32, align 4
%z = alloca i32, align 4
%0 = bitcast [4 x i32]* %v to i8*
%1 = bitcast i32* %x to i8*
%2 = bitcast i32* %y to i8*
%3 = bitcast i32* %z to i8*
%arraydecay = getelementptr inbounds [4 x i32], [4 x i32]* %v, i32 0, i32 0
%call = call i32 @u(i32* nonnull %arraydecay, i32* nonnull %x, i32* nonnull %y, %struct.S* byval nonnull align 4 @s, %struct.S* byval nonnull align 4 @s)
%call2 = call i32 @u(i32* nonnull %arraydecay, i32* nonnull %y, i32* nonnull %z, %struct.S* byval nonnull align 4 @s, %struct.S* byval nonnull align 4 @s)
%add = add nsw i32 %call2, %call
ret i32 %add
}
; CHECK-LABEL: test_local_moving_sp
; Locals area
; CHECK: sub sp, #36
; Setup BP
; CHECK: mov r6, sp
; Outoging arguments
; CHECK: sub sp, #508
; CHECK-NEXT: sub sp, #508
; CHECK-NEXT: sub sp, #8
; Argument addresses computed relative to BP
; CHECK: adds r0, r6, #7
; CHECK-NEXT: adds r0, #13
; CHECK: adds r1, r6, #7
; CHECK-NEXT: adds r1, #9
; CHECK: adds r5, r6, #7
; CHECK-NEXT: adds r5, #5
; CHECK: bl u
; Stack restored before next call
; CHECK: add sp, #508
; CHECK-NEXT: add sp, #508
; CHECK-NEXT: add sp, #8
; CHECK: bl u
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