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ARM: fix Thumb2 CodeGen for ldrex with folded frame-index.

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Because t2LDREX (& t2STREX) were marked as AddrModeNone, but did allow a
FrameIndex operand, rewriteT2FrameIndex asserted. This gives them a
proper addressing-mode and tells the rewriter about it so that encodable
offsets are exploited and others are rejected.

Should fix PR38828.

llvm-svn: 341642
This commit is contained in:
Tim Northover 2018-09-07 09:21:25 +00:00
parent d0446d3d9b
commit 5b3d6373ba
7 changed files with 133 additions and 3 deletions
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1
lib/Target/ARM/ARMFrameLowering.cpp
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@ -1516,6 +1516,7 @@ static unsigned estimateRSStackSizeLimit(MachineFunction &MF,
break;
case ARMII::AddrMode5:
case ARMII::AddrModeT2_i8s4:
case ARMII::AddrModeT2_ldrex:
Limit = std::min(Limit, ((1U << 8) - 1) * 4);
break;
case ARMII::AddrModeT2_i12:

1
lib/Target/ARM/ARMInstrFormats.td
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@ -109,6 +109,7 @@ def AddrModeT2_pc : AddrMode<14>;
def AddrModeT2_i8s4 : AddrMode<15>;
def AddrMode_i12 : AddrMode<16>;
def AddrMode5FP16 : AddrMode<17>;
def AddrModeT2_ldrex : AddrMode<18>;
// Load / store index mode.
class IndexMode<bits<2> val> {

4
lib/Target/ARM/ARMInstrThumb2.td
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@ -3275,7 +3275,7 @@ def t2LDREXH : T2I_ldrex<0b0101, (outs rGPR:$Rt), (ins addr_offset_none:$addr),
[(set rGPR:$Rt, (ldrex_2 addr_offset_none:$addr))]>,
Requires<[IsThumb, HasV8MBaseline]>;
def t2LDREX : Thumb2I<(outs rGPR:$Rt), (ins t2addrmode_imm0_1020s4:$addr),
AddrModeNone, 4, NoItinerary,
AddrModeT2_ldrex, 4, NoItinerary,
"ldrex", "\t$Rt, $addr", "",
[(set rGPR:$Rt, (ldrex_4 t2addrmode_imm0_1020s4:$addr))]>,
Requires<[IsThumb, HasV8MBaseline]> {
@ -3354,7 +3354,7 @@ def t2STREXH : T2I_strex<0b0101, (outs rGPR:$Rd),
def t2STREX : Thumb2I<(outs rGPR:$Rd), (ins rGPR:$Rt,
t2addrmode_imm0_1020s4:$addr),
AddrModeNone, 4, NoItinerary,
AddrModeT2_ldrex, 4, NoItinerary,
"strex", "\t$Rd, $Rt, $addr", "",
[(set rGPR:$Rd,
(strex_4 rGPR:$Rt, t2addrmode_imm0_1020s4:$addr))]>,

4
lib/Target/ARM/MCTargetDesc/ARMBaseInfo.h
View File

@ -201,7 +201,8 @@ namespace ARMII {
AddrModeT2_pc = 14, // +/- i12 for pc relative data
AddrModeT2_i8s4 = 15, // i8 * 4
AddrMode_i12 = 16,
AddrMode5FP16 = 17 // i8 * 2
AddrMode5FP16 = 17, // i8 * 2
AddrModeT2_ldrex = 18, // i8 * 4, with unscaled offset in MCInst
};
inline static const char *AddrModeToString(AddrMode addrmode) {
@ -224,6 +225,7 @@ namespace ARMII {
case AddrModeT2_pc: return "AddrModeT2_pc";
case AddrModeT2_i8s4: return "AddrModeT2_i8s4";
case AddrMode_i12: return "AddrMode_i12";
case AddrModeT2_ldrex:return "AddrModeT2_ldrex";
}
}

5
lib/Target/ARM/Thumb2InstrInfo.cpp
View File

@ -621,6 +621,11 @@ bool llvm::rewriteT2FrameIndex(MachineInstr &MI, unsigned FrameRegIdx,
// MCInst operand expects already scaled value.
Scale = 1;
assert((Offset & 3) == 0 && "Can't encode this offset!");
} else if (AddrMode == ARMII::AddrModeT2_ldrex) {
Offset += MI.getOperand(FrameRegIdx + 1).getImm() * 4;
NumBits = 8; // 8 bits scaled by 4
Scale = 4;
assert((Offset & 3) == 0 && "Can't encode this offset!");
} else {
llvm_unreachable("Unsupported addressing mode!");
}

36
test/CodeGen/ARM/ldrex-frame-size.ll Normal file
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@ -0,0 +1,36 @@
; RUN: llc -mtriple=thumbv7-linux-gnueabi -o - %s | FileCheck %s
; This alloca is just large enough that FrameLowering decides it needs a frame
; to guarantee access, based on the range of ldrex.
; The actual alloca size is a bit of black magic, unfortunately: the real
; maximum accessible is 1020, but FrameLowering adds 16 bytes to its estimated
; stack size just because so the alloca is not actually the what the limit gets
; compared to. The important point is that we don't go up to ~4096, which is the
; default with no strange instructions.
define void @test_large_frame() {
; CHECK-LABEL: test_large_frame:
; CHECK: push
; CHECK: sub.w sp, sp, #1004
%ptr = alloca i32, i32 251
%addr = getelementptr i32, i32* %ptr, i32 1
call i32 @llvm.arm.ldrex.p0i32(i32* %addr)
ret void
}
; This alloca is just is just the other side of the limit, so no frame
define void @test_small_frame() {
; CHECK-LABEL: test_small_frame:
; CHECK-NOT: push
; CHECK: sub.w sp, sp, #1000
%ptr = alloca i32, i32 250
%addr = getelementptr i32, i32* %ptr, i32 1
call i32 @llvm.arm.ldrex.p0i32(i32* %addr)
ret void
}
declare i32 @llvm.arm.ldrex.p0i32(i32*)

85
test/CodeGen/ARM/ldstrex.ll
View File

@ -142,6 +142,91 @@ define void @excl_addrmode() {
ret void
}
define void @test_excl_addrmode_folded() {
; CHECK-LABEL: test_excl_addrmode_folded:
%local = alloca i8, i32 4096
%local.0 = getelementptr i8, i8* %local, i32 4
%local32.0 = bitcast i8* %local.0 to i32*
call i32 @llvm.arm.ldrex.p0i32(i32* %local32.0)
call i32 @llvm.arm.strex.p0i32(i32 0, i32* %local32.0)
; CHECK-T2ADDRMODE: ldrex {{r[0-9]+}}, [sp, #4]
; CHECK-T2ADDRMODE: strex {{r[0-9]+}}, {{r[0-9]+}}, [sp, #4]
%local.1 = getelementptr i8, i8* %local, i32 1020
%local32.1 = bitcast i8* %local.1 to i32*
call i32 @llvm.arm.ldrex.p0i32(i32* %local32.1)
call i32 @llvm.arm.strex.p0i32(i32 0, i32* %local32.1)
; CHECK-T2ADDRMODE: ldrex {{r[0-9]+}}, [sp, #1020]
; CHECK-T2ADDRMODE: strex {{r[0-9]+}}, {{r[0-9]+}}, [sp, #1020]
ret void
}
define void @test_excl_addrmode_range() {
; CHECK-LABEL: test_excl_addrmode_range:
%local = alloca i8, i32 4096
%local.0 = getelementptr i8, i8* %local, i32 1024
%local32.0 = bitcast i8* %local.0 to i32*
call i32 @llvm.arm.ldrex.p0i32(i32* %local32.0)
call i32 @llvm.arm.strex.p0i32(i32 0, i32* %local32.0)
; CHECK-T2ADDRMODE: mov r[[TMP:[0-9]+]], sp
; CHECK-T2ADDRMODE: add.w r[[ADDR:[0-9]+]], r[[TMP]], #1024
; CHECK-T2ADDRMODE: ldrex {{r[0-9]+}}, [r[[ADDR]]]
; CHECK-T2ADDRMODE: strex {{r[0-9]+}}, {{r[0-9]+}}, [r[[ADDR]]]
ret void
}
define void @test_excl_addrmode_align() {
; CHECK-LABEL: test_excl_addrmode_align:
%local = alloca i8, i32 4096
%local.0 = getelementptr i8, i8* %local, i32 2
%local32.0 = bitcast i8* %local.0 to i32*
call i32 @llvm.arm.ldrex.p0i32(i32* %local32.0)
call i32 @llvm.arm.strex.p0i32(i32 0, i32* %local32.0)
; CHECK-T2ADDRMODE: mov r[[ADDR:[0-9]+]], sp
; CHECK-T2ADDRMODE: adds r[[ADDR:[0-9]+]], #2
; CHECK-T2ADDRMODE: ldrex {{r[0-9]+}}, [r[[ADDR]]]
; CHECK-T2ADDRMODE: strex {{r[0-9]+}}, {{r[0-9]+}}, [r[[ADDR]]]
ret void
}
define void @test_excl_addrmode_sign() {
; CHECK-LABEL: test_excl_addrmode_sign:
%local = alloca i8, i32 4096
%local.0 = getelementptr i8, i8* %local, i32 -4
%local32.0 = bitcast i8* %local.0 to i32*
call i32 @llvm.arm.ldrex.p0i32(i32* %local32.0)
call i32 @llvm.arm.strex.p0i32(i32 0, i32* %local32.0)
; CHECK-T2ADDRMODE: mov r[[ADDR:[0-9]+]], sp
; CHECK-T2ADDRMODE: subs r[[ADDR:[0-9]+]], #4
; CHECK-T2ADDRMODE: ldrex {{r[0-9]+}}, [r[[ADDR]]]
; CHECK-T2ADDRMODE: strex {{r[0-9]+}}, {{r[0-9]+}}, [r[[ADDR]]]
ret void
}
define void @test_excl_addrmode_combination() {
; CHECK-LABEL: test_excl_addrmode_combination:
%local = alloca i8, i32 4096
%unused = alloca i8, i32 64
%local.0 = getelementptr i8, i8* %local, i32 4
%local32.0 = bitcast i8* %local.0 to i32*
call i32 @llvm.arm.ldrex.p0i32(i32* %local32.0)
call i32 @llvm.arm.strex.p0i32(i32 0, i32* %local32.0)
; CHECK-T2ADDRMODE: ldrex {{r[0-9]+}}, [sp, #68]
; CHECK-T2ADDRMODE: strex {{r[0-9]+}}, {{r[0-9]+}}, [sp, #68]
ret void
}
; LLVM should know, even across basic blocks, that ldrex is setting the high
; bits of its i32 to 0. There should be no zero-extend operation.
define zeroext i8 @test_cross_block_zext_i8(i1 %tst, i8* %addr) {