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[X86] Resolve FIXME: Create cld only when needed
Only use cld when we also have rep instructions or are calling a function.
1 parent f40ee6e commit 91c0f9e

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4 files changed

+26
-25
lines changed

4 files changed

+26
-25
lines changed

‎llvm/lib/Target/X86/X86FrameLowering.cpp

Lines changed: 26 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -2194,13 +2194,35 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF,
21942194
// flag (DF in EFLAGS register). Clear this flag by creating "cld" instruction
21952195
// in each prologue of interrupt handler function.
21962196
//
2197-
// FIXME: Create "cld" instruction only in these cases:
2197+
// Create "cld" instruction only in these cases:
21982198
// 1. The interrupt handling function uses any of the "rep" instructions.
21992199
// 2. Interrupt handling function calls another function.
22002200
//
2201-
if (Fn.getCallingConv() == CallingConv::X86_INTR)
2202-
BuildMI(MBB, MBBI, DL, TII.get(X86::CLD))
2203-
.setMIFlag(MachineInstr::FrameSetup);
2201+
if (Fn.getCallingConv() == CallingConv::X86_INTR) {
2202+
bool NeedsCLD = false;
2203+
2204+
// Check if the function calls another function.
2205+
for (const BasicBlock &BB : Fn) {
2206+
for (const Instruction &I : BB) {
2207+
if (isa<CallInst>(I)) {
2208+
NeedsCLD = true;
2209+
break;
2210+
}
2211+
2212+
// Check for rep opcode.
2213+
unsigned Opcode = I.getOpcode();
2214+
if (X86::REP_MOVSB_32 <= Opcode && Opcode <= X86::REP_STOSW_64) {
2215+
NeedsCLD = true;
2216+
break;
2217+
}
2218+
}
2219+
}
2220+
2221+
if (NeedsCLD) {
2222+
BuildMI(MBB, MBBI, DL, TII.get(X86::CLD))
2223+
.setMIFlag(MachineInstr::FrameSetup);
2224+
}
2225+
}
22042226

22052227
// At this point we know if the function has WinCFI or not.
22062228
MF.setHasWinCFI(HasWinCFI);

‎llvm/test/CodeGen/X86/x86-32-intrcc.ll

Lines changed: 0 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -149,7 +149,6 @@ define x86_intrcc void @test_isr_x87(ptr byval(%struct.interrupt_frame) %frame)
149149
; CHECK-NEXT: pushl %ebp
150150
; CHECK-NEXT: movl %esp, %ebp
151151
; CHECK-NEXT: andl $-16, %esp
152-
; CHECK-NEXT: cld
153152
; CHECK-NEXT: fldt f80
154153
; CHECK-NEXT: fld1
155154
; CHECK-NEXT: faddp %st, %st(1)
@@ -163,7 +162,6 @@ define x86_intrcc void @test_isr_x87(ptr byval(%struct.interrupt_frame) %frame)
163162
; CHECK0-NEXT: pushl %ebp
164163
; CHECK0-NEXT: movl %esp, %ebp
165164
; CHECK0-NEXT: andl $-16, %esp
166-
; CHECK0-NEXT: cld
167165
; CHECK0-NEXT: fldt f80
168166
; CHECK0-NEXT: fld1
169167
; CHECK0-NEXT: faddp %st, %st(1)
@@ -188,7 +186,6 @@ define dso_local x86_intrcc void @test_fp_1(ptr byval(%struct.interrupt_frame) %
188186
; CHECK-NEXT: pushl %ecx
189187
; CHECK-NEXT: pushl %eax
190188
; CHECK-NEXT: andl $-16, %esp
191-
; CHECK-NEXT: cld
192189
; CHECK-NEXT: leal 20(%ebp), %eax
193190
; CHECK-NEXT: leal 4(%ebp), %ecx
194191
; CHECK-NEXT: movl %ecx, sink_address
@@ -206,7 +203,6 @@ define dso_local x86_intrcc void @test_fp_1(ptr byval(%struct.interrupt_frame) %
206203
; CHECK0-NEXT: pushl %ecx
207204
; CHECK0-NEXT: pushl %eax
208205
; CHECK0-NEXT: andl $-16, %esp
209-
; CHECK0-NEXT: cld
210206
; CHECK0-NEXT: leal 4(%ebp), %ecx
211207
; CHECK0-NEXT: movl %ecx, %eax
212208
; CHECK0-NEXT: addl $16, %eax
@@ -234,7 +230,6 @@ define dso_local x86_intrcc void @test_fp_2(ptr byval(%struct.interrupt_frame) %
234230
; CHECK-NEXT: pushl %ecx
235231
; CHECK-NEXT: pushl %eax
236232
; CHECK-NEXT: andl $-16, %esp
237-
; CHECK-NEXT: cld
238233
; CHECK-NEXT: movl 4(%ebp), %eax
239234
; CHECK-NEXT: leal 24(%ebp), %ecx
240235
; CHECK-NEXT: leal 8(%ebp), %edx
@@ -257,7 +252,6 @@ define dso_local x86_intrcc void @test_fp_2(ptr byval(%struct.interrupt_frame) %
257252
; CHECK0-NEXT: pushl %ecx
258253
; CHECK0-NEXT: pushl %eax
259254
; CHECK0-NEXT: andl $-16, %esp
260-
; CHECK0-NEXT: cld
261255
; CHECK0-NEXT: movl 4(%ebp), %eax
262256
; CHECK0-NEXT: leal 8(%ebp), %edx
263257
; CHECK0-NEXT: movl %edx, %ecx
@@ -288,7 +282,6 @@ define x86_intrcc void @test_copy_elide(ptr byval(%struct.interrupt_frame) %fram
288282
; CHECK-NEXT: movl %esp, %ebp
289283
; CHECK-NEXT: pushl %eax
290284
; CHECK-NEXT: andl $-16, %esp
291-
; CHECK-NEXT: cld
292285
; CHECK-NEXT: leal 4(%ebp), %eax
293286
; CHECK-NEXT: movl %eax, sink_address
294287
; CHECK-NEXT: leal -4(%ebp), %esp
@@ -303,7 +296,6 @@ define x86_intrcc void @test_copy_elide(ptr byval(%struct.interrupt_frame) %fram
303296
; CHECK0-NEXT: movl %esp, %ebp
304297
; CHECK0-NEXT: pushl %eax
305298
; CHECK0-NEXT: andl $-16, %esp
306-
; CHECK0-NEXT: cld
307299
; CHECK0-NEXT: movl 4(%ebp), %eax
308300
; CHECK0-NEXT: leal 4(%ebp), %eax
309301
; CHECK0-NEXT: movl %eax, sink_address
@@ -358,7 +350,6 @@ define x86_intrcc void @test_isr_realign(ptr byval(%struct.interrupt_frame) %fra
358350
; CHECK-NEXT: pushl %eax
359351
; CHECK-NEXT: andl $-32, %esp
360352
; CHECK-NEXT: subl $32, %esp
361-
; CHECK-NEXT: cld
362353
; CHECK-NEXT: movl 4(%ebp), %eax
363354
; CHECK-NEXT: movl %eax, (%esp)
364355
; CHECK-NEXT: leal -4(%ebp), %esp
@@ -374,7 +365,6 @@ define x86_intrcc void @test_isr_realign(ptr byval(%struct.interrupt_frame) %fra
374365
; CHECK0-NEXT: pushl %eax
375366
; CHECK0-NEXT: andl $-32, %esp
376367
; CHECK0-NEXT: subl $32, %esp
377-
; CHECK0-NEXT: cld
378368
; CHECK0-NEXT: movl 4(%ebp), %eax
379369
; CHECK0-NEXT: movl %eax, (%esp)
380370
; CHECK0-NEXT: leal -4(%ebp), %esp

‎llvm/test/CodeGen/X86/x86-64-intrcc-uintr.ll

Lines changed: 0 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -21,28 +21,24 @@ define dso_local x86_intrcc void @test_uintr_isr_cc_empty(ptr nocapture byval(%s
2121
; CHECK-USER-LABEL: test_uintr_isr_cc_empty:
2222
; CHECK-USER: # %bb.0: # %entry
2323
; CHECK-USER-NEXT: pushq %rax
24-
; CHECK-USER-NEXT: cld
2524
; CHECK-USER-NEXT: addq $16, %rsp
2625
; CHECK-USER-NEXT: uiret
2726
;
2827
; CHECK0-USER-LABEL: test_uintr_isr_cc_empty:
2928
; CHECK0-USER: # %bb.0: # %entry
3029
; CHECK0-USER-NEXT: pushq %rax
31-
; CHECK0-USER-NEXT: cld
3230
; CHECK0-USER-NEXT: addq $16, %rsp
3331
; CHECK0-USER-NEXT: uiret
3432
;
3533
; CHECK-KERNEL-LABEL: test_uintr_isr_cc_empty:
3634
; CHECK-KERNEL: # %bb.0: # %entry
3735
; CHECK-KERNEL-NEXT: pushq %rax
38-
; CHECK-KERNEL-NEXT: cld
3936
; CHECK-KERNEL-NEXT: addq $16, %rsp
4037
; CHECK-KERNEL-NEXT: iretq
4138
;
4239
; CHECK0-KERNEL-LABEL: test_uintr_isr_cc_empty:
4340
; CHECK0-KERNEL: # %bb.0: # %entry
4441
; CHECK0-KERNEL-NEXT: pushq %rax
45-
; CHECK0-KERNEL-NEXT: cld
4642
; CHECK0-KERNEL-NEXT: addq $16, %rsp
4743
; CHECK0-KERNEL-NEXT: iretq
4844
entry:
@@ -75,7 +71,6 @@ define dso_local x86_intrcc void @test_uintr_isr_cc_args(ptr nocapture readonly
7571
; CHECK-USER-NEXT: pushq %rax
7672
; CHECK-USER-NEXT: pushq %rdx
7773
; CHECK-USER-NEXT: pushq %rcx
78-
; CHECK-USER-NEXT: cld
7974
; CHECK-USER-NEXT: movq 32(%rsp), %rax
8075
; CHECK-USER-NEXT: movq 40(%rsp), %rcx
8176
; CHECK-USER-NEXT: movq 48(%rsp), %rdx
@@ -96,7 +91,6 @@ define dso_local x86_intrcc void @test_uintr_isr_cc_args(ptr nocapture readonly
9691
; CHECK0-USER-NEXT: pushq %rax
9792
; CHECK0-USER-NEXT: pushq %rdx
9893
; CHECK0-USER-NEXT: pushq %rcx
99-
; CHECK0-USER-NEXT: cld
10094
; CHECK0-USER-NEXT: movq 32(%rsp), %rax
10195
; CHECK0-USER-NEXT: leaq 40(%rsp), %rcx
10296
; CHECK0-USER-NEXT: movq (%rcx), %rdx
@@ -118,7 +112,6 @@ define dso_local x86_intrcc void @test_uintr_isr_cc_args(ptr nocapture readonly
118112
; CHECK-KERNEL-NEXT: pushq %rax
119113
; CHECK-KERNEL-NEXT: pushq %rdx
120114
; CHECK-KERNEL-NEXT: pushq %rcx
121-
; CHECK-KERNEL-NEXT: cld
122115
; CHECK-KERNEL-NEXT: movq 32(%rsp), %rax
123116
; CHECK-KERNEL-NEXT: movq 40(%rsp), %rcx
124117
; CHECK-KERNEL-NEXT: movq 48(%rsp), %rdx
@@ -139,7 +132,6 @@ define dso_local x86_intrcc void @test_uintr_isr_cc_args(ptr nocapture readonly
139132
; CHECK0-KERNEL-NEXT: pushq %rax
140133
; CHECK0-KERNEL-NEXT: pushq %rdx
141134
; CHECK0-KERNEL-NEXT: pushq %rcx
142-
; CHECK0-KERNEL-NEXT: cld
143135
; CHECK0-KERNEL-NEXT: movq 32(%rsp), %rax
144136
; CHECK0-KERNEL-NEXT: leaq 40(%rsp), %rcx
145137
; CHECK0-KERNEL-NEXT: movq (%rcx), %rdx

‎llvm/test/CodeGen/X86/x86-64-intrcc.ll

Lines changed: 0 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -114,7 +114,6 @@ define dso_local x86_intrcc void @test_fp_1(ptr byval(%struct.interrupt_frame) %
114114
; CHECK: # %bb.0: # %entry
115115
; CHECK-NEXT: pushq %rbp
116116
; CHECK-NEXT: movq %rsp, %rbp
117-
; CHECK: cld
118117
; CHECK-DAG: leaq 8(%rbp), %[[R1:[^ ]*]]
119118
; CHECK-DAG: leaq 40(%rbp), %[[R2:[^ ]*]]
120119
; CHECK: movq %[[R1]], sink_address
@@ -136,7 +135,6 @@ define dso_local x86_intrcc void @test_fp_2(ptr byval(%struct.interrupt_frame) %
136135
; CHECK-NEXT: pushq %rax
137136
; CHECK-NEXT: pushq %rbp
138137
; CHECK-NEXT: movq %rsp, %rbp
139-
; CHECK: cld
140138
; CHECK-DAG: movq 16(%rbp), %[[R3:[^ ]*]]
141139
; CHECK-DAG: leaq 24(%rbp), %[[R1:[^ ]*]]
142140
; CHECK-DAG: leaq 56(%rbp), %[[R2:[^ ]*]]
@@ -164,7 +162,6 @@ define x86_intrcc void @test_copy_elide(ptr byval(%struct.interrupt_frame) %fram
164162
; CHECK-NEXT: pushq %rax
165163
; CHECK-NEXT: pushq %rbp
166164
; CHECK-NEXT: movq %rsp, %rbp
167-
; CHECK: cld
168165
; CHECK: leaq 16(%rbp), %[[R1:[^ ]*]]
169166
; CHECK: movq %[[R1]], sink_address(%rip)
170167
entry:

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