[llvm] [AArch64][GlobalISel] Implement selectVaStartAAPCS (PR #106979)

[Matt Arsenault via llvm-commits]

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@@ -0,0 +1,106 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -O0 -mtriple=aarch64-unknown-linux -run-pass=instruction-select -verify-machineinstrs %s -o - | FileCheck %s -check-prefixes=CHECK
+
+--- |
+  target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128-Fn32"
+  target triple = "aarch64-unknown-linux-gnu"
+
+  %struct.__va_list = type { ptr, ptr, ptr, i32, i32 }
+
+  define i32 @va_start(ptr %a, ...) {
+  entry:
+    %ap = alloca %struct.__va_list, align 8
+    call void @llvm.lifetime.start.p0(i64 32, ptr %ap)
+    call void @llvm.va_start.p0(ptr %ap)
+    %vr_offs_p = getelementptr inbounds i8, ptr %ap, i64 28
+    %vr_offs = load i32, ptr %vr_offs_p, align 4
+    ret i32 %vr_offs
+  }
+...
+---
+name:            va_start
+alignment:       16
+exposesReturnsTwice: false
+legalized:       true
+regBankSelected: true
+selected:        false
+failedISel:      false
+tracksRegLiveness: true
+hasWinCFI:       false
+callsEHReturn:   false
+callsUnwindInit: false
+hasEHCatchret:   false
+hasEHScopes:     false
+hasEHFunclets:   false
+isOutlined:      false
+debugInstrRef:   false
+failsVerification: false
+tracksDebugUserValues: false
+registers:
+liveins:
+frameInfo:
+  isFrameAddressTaken: false
+  isReturnAddressTaken: false
+  hasStackMap:     false
+  hasPatchPoint:   false
+  stackSize:       0
+  offsetAdjustment: 0
+  maxAlignment:    16
+  adjustsStack:    false
+  hasCalls:        false
+  stackProtector:  ''
+  functionContext: ''
+  maxCallFrameSize: 4294967295
+  cvBytesOfCalleeSavedRegisters: 0
+  hasOpaqueSPAdjustment: false
+  hasVAStart:      false
+  hasMustTailInVarArgFunc: false
+  hasTailCall:     false
+  isCalleeSavedInfoValid: false
+  localFrameSize:  0
+  savePoint:       ''
+  restorePoint:    ''
+fixedStack:
+  - { id: 0, type: default, offset: 0, size: 4, alignment: 16, stack-id: default,
+      isImmutable: true, isAliased: false, callee-saved-register: '', callee-saved-restored: true,
+      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+stack:
+  - { id: 0, name: '', type: default, offset: 0, size: 56, alignment: 8,
+      stack-id: default, callee-saved-register: '', callee-saved-restored: true,
+      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+  - { id: 1, name: '', type: default, offset: 0, size: 128, alignment: 16,
+      stack-id: default, callee-saved-register: '', callee-saved-restored: true,
+      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+  - { id: 2, name: ap, type: default, offset: 0, size: 32, alignment: 8,
+      stack-id: default, callee-saved-register: '', callee-saved-restored: true,
+      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+entry_values:    []
+callSites:       []
+debugValueSubstitutions: []
+constants:       []
+machineFunctionInfo: {}
+body:             |
+  bb.1.entry:
+    ; CHECK-LABEL: name: va_start
+    ; CHECK: LIFETIME_START %stack.2.ap
+    ; CHECK-NEXT: [[ADDXri:%[0-9]+]]:gpr64sp = ADDXri %stack.2.ap, 0, 0
+    ; CHECK-NEXT: [[ADDXri1:%[0-9]+]]:gpr64common = ADDXri %stack.0, 0, 0
+    ; CHECK-NEXT: STRXui [[ADDXri1]], [[ADDXri]], 0 :: (store (s64) into %ir.ap)
+    ; CHECK-NEXT: [[ADDXri2:%[0-9]+]]:gpr64common = ADDXri %stack.0, 0, 0
+    ; CHECK-NEXT: STRXui [[ADDXri2]], [[ADDXri]], 1 :: (store (s64) into %ir.ap + 8)
+    ; CHECK-NEXT: [[ADDXri3:%[0-9]+]]:gpr64common = ADDXri %stack.0, 0, 0
+    ; CHECK-NEXT: STRXui [[ADDXri3]], [[ADDXri]], 2 :: (store (s64) into %ir.ap + 16)
+    ; CHECK-NEXT: [[MOVi32imm:%[0-9]+]]:gpr32 = MOVi32imm 0
+    ; CHECK-NEXT: STRWui [[MOVi32imm]], [[ADDXri]], 6 :: (store (s32) into %ir.ap + 24, align 8)
+    ; CHECK-NEXT: [[MOVi32imm1:%[0-9]+]]:gpr32 = MOVi32imm 0
+    ; CHECK-NEXT: STRWui [[MOVi32imm1]], [[ADDXri]], 7 :: (store (s32) into %ir.ap + 28)
+    ; CHECK-NEXT: [[LDRWui:%[0-9]+]]:gpr32 = LDRWui %stack.2.ap, 7 :: (dereferenceable load (s32) from %ir.vr_offs_p)
+    ; CHECK-NEXT: $w0 = COPY [[LDRWui]]
+    LIFETIME_START %stack.2.ap
+    %35:gpr(p0) = G_FRAME_INDEX %stack.2.ap
----------------
arsenm wrote:

compact the register numbers, run-pass=none will do that 

https://github.com/llvm/llvm-project/pull/106979