[llvm] 1a71668 - [AArch64] Fix stack probing clobbering flags (#81879)
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Wed Feb 21 05:58:08 PST 2024
Author: Momchil Velikov
Date: 2024-02-21T13:58:04Z
New Revision: 1a7166833d38a2a5c26eacecd13833a9a15e3b3d
URL: https://github.com/llvm/llvm-project/commit/1a7166833d38a2a5c26eacecd13833a9a15e3b3d
DIFF: https://github.com/llvm/llvm-project/commit/1a7166833d38a2a5c26eacecd13833a9a15e3b3d.diff
LOG: [AArch64] Fix stack probing clobbering flags (#81879)
Certain stack probing sequences might clobber flags, then we can't use a
block as a prologue if the flags register is a live-in on entry to that
block.
Added:
llvm/test/CodeGen/AArch64/stack-probing-shrink-wrap.mir
Modified:
llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp b/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
index d98750e09d4e36..3485edb69c910c 100644
--- a/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
@@ -1061,6 +1061,12 @@ bool AArch64FrameLowering::canUseAsPrologue(
return false;
}
+ // Certain stack probing sequences might clobber flags, then we can't use
+ // the block as a prologue if the flags register is a live-in.
+ if (MF->getInfo<AArch64FunctionInfo>()->hasStackProbing() &&
+ MBB.isLiveIn(AArch64::NZCV))
+ return false;
+
// Don't need a scratch register if we're not going to re-align the stack or
// emit stack probes.
if (!RegInfo->hasStackRealignment(*MF) && !TLI->hasInlineStackProbe(*MF))
diff --git a/llvm/test/CodeGen/AArch64/stack-probing-shrink-wrap.mir b/llvm/test/CodeGen/AArch64/stack-probing-shrink-wrap.mir
new file mode 100644
index 00000000000000..83aa90d389a4a2
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/stack-probing-shrink-wrap.mir
@@ -0,0 +1,107 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 4
+# RUN: llc %s --start-before=shrink-wrap --stop-after=prologepilog -o - | FileCheck %s
+--- |
+ target triple = "aarch64-linux"
+
+ define void @f(i32 %n) #0 {
+ entry:
+ %a = alloca i8, i32 150000, align 8
+ %c0 = icmp sle i32 %n, 1
+ br i1 %c0, label %if.then1, label %exit
+
+ if.then1: ; preds = %entry
+ %0 = icmp sle i32 %n, 1
+ %v = select i1 %0, i32 0, i32 1
+ call void @g(ptr %a, i32 %v)
+ br label %exit
+
+ exit: ; preds = %if.then1, %entry
+ ret void
+ }
+
+ declare void @g(...)
+
+ attributes #0 = { nounwind "probe-stack"="inline-asm" "stack-probe-size"="4096" }
+
+...
+---
+name: f
+alignment: 4
+tracksRegLiveness: true
+liveins:
+ - { reg: '$w0', virtual-reg: '' }
+frameInfo:
+ localFrameSize: 150000
+stack:
+ - { id: 0, name: a, type: default, offset: 0, size: 150000, alignment: 8,
+ stack-id: default, callee-saved-register: '', callee-saved-restored: true,
+ local-offset: -150000, debug-info-variable: '', debug-info-expression: '',
+ debug-info-location: '' }
+entry_values: []
+callSites: []
+debugValueSubstitutions: []
+constants: []
+machineFunctionInfo: {}
+body: |
+ ; CHECK-LABEL: name: f
+ ; CHECK: bb.0.entry:
+ ; CHECK-NEXT: successors: %bb.3(0x80000000)
+ ; CHECK-NEXT: liveins: $w0, $lr
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: early-clobber $sp = frame-setup STPXpre killed $fp, killed $lr, $sp, -2 :: (store (s64) into %stack.2), (store (s64) into %stack.1)
+ ; CHECK-NEXT: $x9 = frame-setup SUBXri $sp, 36, 12
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: bb.3.entry:
+ ; CHECK-NEXT: successors: %bb.4(0x40000000), %bb.3(0x40000000)
+ ; CHECK-NEXT: liveins: $w0, $x9
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: $sp = frame-setup SUBXri $sp, 1, 12
+ ; CHECK-NEXT: frame-setup STRXui $xzr, $sp, 0
+ ; CHECK-NEXT: $xzr = frame-setup SUBSXrx64 $sp, $x9, 24, implicit-def $nzcv
+ ; CHECK-NEXT: frame-setup Bcc 1, %bb.3, implicit $nzcv
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: bb.4.entry:
+ ; CHECK-NEXT: successors: %bb.1(0x40000000), %bb.2(0x40000000)
+ ; CHECK-NEXT: liveins: $w0
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: $sp = frame-setup SUBXri $sp, 2544, 0
+ ; CHECK-NEXT: frame-setup STRXui $xzr, $sp, 0
+ ; CHECK-NEXT: dead $wzr = SUBSWri killed renamable $w0, 1, 0, implicit-def $nzcv
+ ; CHECK-NEXT: Bcc 12, %bb.2, implicit $nzcv
+ ; CHECK-NEXT: B %bb.1
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: bb.1.if.then1:
+ ; CHECK-NEXT: successors: %bb.2(0x80000000)
+ ; CHECK-NEXT: liveins: $nzcv
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: renamable $w1 = CSINCWr $wzr, $wzr, 13, implicit killed $nzcv
+ ; CHECK-NEXT: $x0 = ADDXri $sp, 0, 0
+ ; CHECK-NEXT: BL @g, csr_aarch64_aapcs, implicit-def dead $lr, implicit $sp, implicit $x0, implicit $w1, implicit-def $sp
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: bb.2.exit:
+ ; CHECK-NEXT: $sp = frame-destroy ADDXri $sp, 36, 12
+ ; CHECK-NEXT: $sp = frame-destroy ADDXri $sp, 2544, 0
+ ; CHECK-NEXT: early-clobber $sp, $fp, $lr = frame-destroy LDPXpost $sp, 2 :: (load (s64) from %stack.2), (load (s64) from %stack.1)
+ ; CHECK-NEXT: RET_ReallyLR
+ bb.0.entry:
+ successors: %bb.1(0x40000000), %bb.2(0x40000000)
+ liveins: $w0
+
+ dead $wzr = SUBSWri killed renamable $w0, 1, 0, implicit-def $nzcv
+ Bcc 12, %bb.2, implicit $nzcv
+ B %bb.1
+
+ bb.1.if.then1:
+ successors: %bb.2(0x80000000)
+ liveins: $nzcv
+
+ renamable $w1 = CSINCWr $wzr, $wzr, 13, implicit killed $nzcv
+ ADJCALLSTACKDOWN 0, 0, implicit-def dead $sp, implicit $sp
+ $x0 = ADDXri %stack.0.a, 0, 0
+ BL @g, csr_aarch64_aapcs, implicit-def dead $lr, implicit $sp, implicit $x0, implicit $w1, implicit-def $sp
+ ADJCALLSTACKUP 0, 0, implicit-def dead $sp, implicit $sp
+
+ bb.2.exit:
+ RET_ReallyLR
+
+...
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