[llvm] [WebAssembly][GlobalISel] Part 2 - CallLowering `lowerFormalArguments` (PR #180263)

[Demetrius Kanios via llvm-commits]

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@@ -0,0 +1,171 @@
+; NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 6
+; RUN: llc -mtriple=wasm32 -mattr=-simd128 -global-isel -stop-after=irtranslator -verify-machineinstrs < %s | FileCheck %s -check-prefixes=NO-SIMD
+; RUN: llc -mtriple=wasm32 -mattr=+simd128,-fp16 -global-isel -stop-after=irtranslator -verify-machineinstrs < %s | FileCheck %s -check-prefixes=SIMD,SIMD-NO-F16
+; RUN: llc -mtriple=wasm32 -mattr=+simd128,+fp16 -global-isel -stop-after=irtranslator -verify-machineinstrs < %s | FileCheck %s -check-prefixes=SIMD,SIMD-F16
+
+define void @test_v16i8_arg(<16 x i8> %arg) {
+  ; NO-SIMD-LABEL: name: test_v16i8_arg
+  ; NO-SIMD: bb.1 (%ir-block.0):
+  ; NO-SIMD-NEXT:   liveins: $arguments
+  ; NO-SIMD-NEXT: {{  $}}
+  ; NO-SIMD-NEXT:   [[ARGUMENT_i32_:%[0-9]+]]:i32(s32) = ARGUMENT_i32 0, implicit $arguments
+  ; NO-SIMD-NEXT:   [[ARGUMENT_i32_1:%[0-9]+]]:i32(s32) = ARGUMENT_i32 1, implicit $arguments
+  ; NO-SIMD-NEXT:   [[ARGUMENT_i32_2:%[0-9]+]]:i32(s32) = ARGUMENT_i32 2, implicit $arguments
+  ; NO-SIMD-NEXT:   [[ARGUMENT_i32_3:%[0-9]+]]:i32(s32) = ARGUMENT_i32 3, implicit $arguments
+  ; NO-SIMD-NEXT:   [[ARGUMENT_i32_4:%[0-9]+]]:i32(s32) = ARGUMENT_i32 4, implicit $arguments
+  ; NO-SIMD-NEXT:   [[ARGUMENT_i32_5:%[0-9]+]]:i32(s32) = ARGUMENT_i32 5, implicit $arguments
+  ; NO-SIMD-NEXT:   [[ARGUMENT_i32_6:%[0-9]+]]:i32(s32) = ARGUMENT_i32 6, implicit $arguments
+  ; NO-SIMD-NEXT:   [[ARGUMENT_i32_7:%[0-9]+]]:i32(s32) = ARGUMENT_i32 7, implicit $arguments
+  ; NO-SIMD-NEXT:   [[ARGUMENT_i32_8:%[0-9]+]]:i32(s32) = ARGUMENT_i32 8, implicit $arguments
+  ; NO-SIMD-NEXT:   [[ARGUMENT_i32_9:%[0-9]+]]:i32(s32) = ARGUMENT_i32 9, implicit $arguments
+  ; NO-SIMD-NEXT:   [[ARGUMENT_i32_10:%[0-9]+]]:i32(s32) = ARGUMENT_i32 10, implicit $arguments
+  ; NO-SIMD-NEXT:   [[ARGUMENT_i32_11:%[0-9]+]]:i32(s32) = ARGUMENT_i32 11, implicit $arguments
+  ; NO-SIMD-NEXT:   [[ARGUMENT_i32_12:%[0-9]+]]:i32(s32) = ARGUMENT_i32 12, implicit $arguments
+  ; NO-SIMD-NEXT:   [[ARGUMENT_i32_13:%[0-9]+]]:i32(s32) = ARGUMENT_i32 13, implicit $arguments
+  ; NO-SIMD-NEXT:   [[ARGUMENT_i32_14:%[0-9]+]]:i32(s32) = ARGUMENT_i32 14, implicit $arguments
+  ; NO-SIMD-NEXT:   [[ARGUMENT_i32_15:%[0-9]+]]:i32(s32) = ARGUMENT_i32 15, implicit $arguments
----------------
QuantumSegfault wrote:

As far as I know, all LLVM arguments are passed directly through individual Wasm-side arguments (ARGUMENT_xxxx eventually lowers to just a `local.get`). Aggregates are recursively split into individual arguments.

There is no stack-spilling. The closest there is to that is the handling for varargs, which are written onto the stack and passed as a single pointer, by necessity.

https://github.com/llvm/llvm-project/pull/180263