[llvm] [WebAssembly] Add support for memcmp expansion (PR #148298)

[Luke Lau via llvm-commits]

================
@@ -0,0 +1,144 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc < %s  -O3 -verify-machineinstrs -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -wasm-keep-registers -mattr=+simd128 | FileCheck %s
+
+target triple = "wasm32-unknown-unknown"
+
+declare i32 @memcmp(ptr, ptr, i32)
+
+define i1 @memcmp_expand_3(ptr %a, ptr %b) {
+; CHECK-LABEL: memcmp_expand_3:
+; CHECK:         .functype memcmp_expand_3 (i32, i32) -> (i32)
+; CHECK-NEXT:  # %bb.0:
+; CHECK-NEXT:    i32.load16_u $push7=, 0($0):p2align=0
+; CHECK-NEXT:    i32.load16_u $push6=, 0($1):p2align=0
+; CHECK-NEXT:    i32.xor $push8=, $pop7, $pop6
+; CHECK-NEXT:    i32.const $push0=, 2
+; CHECK-NEXT:    i32.add $push3=, $0, $pop0
+; CHECK-NEXT:    i32.load8_u $push4=, 0($pop3)
+; CHECK-NEXT:    i32.const $push13=, 2
+; CHECK-NEXT:    i32.add $push1=, $1, $pop13
+; CHECK-NEXT:    i32.load8_u $push2=, 0($pop1)
+; CHECK-NEXT:    i32.xor $push5=, $pop4, $pop2
+; CHECK-NEXT:    i32.or $push9=, $pop8, $pop5
+; CHECK-NEXT:    i32.const $push10=, 65535
+; CHECK-NEXT:    i32.and $push11=, $pop9, $pop10
+; CHECK-NEXT:    i32.eqz $push12=, $pop11
+; CHECK-NEXT:    return $pop12
+  %cmp_3 = call i32 @memcmp(ptr %a, ptr %b, i32 3)
+  %res = icmp eq i32 %cmp_3, 0
+  ret i1 %res
+}
+
+define i1 @memcmp_expand_5(ptr %a, ptr %b) {
+; CHECK-LABEL: memcmp_expand_5:
+; CHECK:         .functype memcmp_expand_5 (i32, i32) -> (i32)
+; CHECK-NEXT:  # %bb.0:
+; CHECK-NEXT:    i32.load $push7=, 0($0):p2align=0
+; CHECK-NEXT:    i32.load $push6=, 0($1):p2align=0
+; CHECK-NEXT:    i32.xor $push8=, $pop7, $pop6
+; CHECK-NEXT:    i32.const $push0=, 4
+; CHECK-NEXT:    i32.add $push3=, $0, $pop0
+; CHECK-NEXT:    i32.load8_u $push4=, 0($pop3)
+; CHECK-NEXT:    i32.const $push11=, 4
+; CHECK-NEXT:    i32.add $push1=, $1, $pop11
+; CHECK-NEXT:    i32.load8_u $push2=, 0($pop1)
+; CHECK-NEXT:    i32.xor $push5=, $pop4, $pop2
+; CHECK-NEXT:    i32.or $push9=, $pop8, $pop5
+; CHECK-NEXT:    i32.eqz $push10=, $pop9
+; CHECK-NEXT:    return $pop10
+  %cmp_5 = call i32 @memcmp(ptr %a, ptr %b, i32 5)
+  %res = icmp eq i32 %cmp_5, 0
+  ret i1 %res
+}
+
+define i1 @memcmp_expand_7(ptr %a, ptr %b) {
+; CHECK-LABEL: memcmp_expand_7:
+; CHECK:         .functype memcmp_expand_7 (i32, i32) -> (i32)
+; CHECK-NEXT:  # %bb.0:
+; CHECK-NEXT:    i32.load $push7=, 0($0):p2align=0
+; CHECK-NEXT:    i32.load $push6=, 0($1):p2align=0
+; CHECK-NEXT:    i32.xor $push8=, $pop7, $pop6
+; CHECK-NEXT:    i32.const $push0=, 3
+; CHECK-NEXT:    i32.add $push3=, $0, $pop0
+; CHECK-NEXT:    i32.load $push4=, 0($pop3):p2align=0
+; CHECK-NEXT:    i32.const $push11=, 3
+; CHECK-NEXT:    i32.add $push1=, $1, $pop11
+; CHECK-NEXT:    i32.load $push2=, 0($pop1):p2align=0
+; CHECK-NEXT:    i32.xor $push5=, $pop4, $pop2
+; CHECK-NEXT:    i32.or $push9=, $pop8, $pop5
+; CHECK-NEXT:    i32.eqz $push10=, $pop9
+; CHECK-NEXT:    return $pop10
+  %cmp_7 = call i32 @memcmp(ptr %a, ptr %b, i32 7)
+  %res = icmp eq i32 %cmp_7, 0
+  ret i1 %res
+}
+
+; INFO: Negative test
+; Should not expand even with simd128
+define i1 @memcmp_expand_129(ptr %a, ptr %b) {
+; CHECK-LABEL: memcmp_expand_129:
+; CHECK:         .functype memcmp_expand_129 (i32, i32) -> (i32)
+; CHECK-NEXT:  # %bb.0:
+; CHECK-NEXT:    i32.const $push0=, 129
+; CHECK-NEXT:    call $push1=, memcmp, $0, $1, $pop0
+; CHECK-NEXT:    i32.eqz $push2=, $pop1
+; CHECK-NEXT:    return $pop2
+  %cmp_129 = call i32 @memcmp(ptr %a, ptr %b, i32 129)
+  %res = icmp eq i32 %cmp_129, 0
+  ret i1 %res
+}
+
+define i1 @memcmp_expand_2(ptr %a, ptr %b) {
+; CHECK-LABEL: memcmp_expand_2:
+; CHECK:         .functype memcmp_expand_2 (i32, i32) -> (i32)
+; CHECK-NEXT:  # %bb.0:
+; CHECK-NEXT:    i32.load16_u $push1=, 0($0):p2align=0
+; CHECK-NEXT:    i32.load16_u $push0=, 0($1):p2align=0
+; CHECK-NEXT:    i32.eq $push2=, $pop1, $pop0
+; CHECK-NEXT:    return $pop2
+  %cmp_2 = call i32 @memcmp(ptr %a, ptr %b, i32 2)
+  %res = icmp eq i32 %cmp_2, 0
+  ret i1 %res
+}
+
+
+define i1 @memcmp_expand_8(ptr %a, ptr %b) {
+; CHECK-LABEL: memcmp_expand_8:
+; CHECK:         .functype memcmp_expand_8 (i32, i32) -> (i32)
+; CHECK-NEXT:  # %bb.0:
+; CHECK-NEXT:    i64.load $push1=, 0($0):p2align=0
+; CHECK-NEXT:    i64.load $push0=, 0($1):p2align=0
+; CHECK-NEXT:    i64.eq $push2=, $pop1, $pop0
+; CHECK-NEXT:    return $pop2
+  %cmp_8 = call i32 @memcmp(ptr %a, ptr %b, i32 8)
+  %res = icmp eq i32 %cmp_8, 0
+  ret i1 %res
+}
+
+
+; TODO: Should be using a single load i64x2 or equivalent in bitsizes
+define i1 @memcmp_expand_16(ptr %a, ptr %b) {
+; CHECK-LABEL: memcmp_expand_16:
+; CHECK:         .functype memcmp_expand_16 (i32, i32) -> (i32)
+; CHECK-NEXT:  # %bb.0:
+; CHECK-NEXT:    i64.load $push7=, 0($0):p2align=0
+; CHECK-NEXT:    i64.load $push6=, 0($1):p2align=0
+; CHECK-NEXT:    i64.xor $push8=, $pop7, $pop6
+; CHECK-NEXT:    i32.const $push0=, 8
+; CHECK-NEXT:    i32.add $push3=, $0, $pop0
+; CHECK-NEXT:    i64.load $push4=, 0($pop3):p2align=0
+; CHECK-NEXT:    i32.const $push11=, 8
+; CHECK-NEXT:    i32.add $push1=, $1, $pop11
+; CHECK-NEXT:    i64.load $push2=, 0($pop1):p2align=0
+; CHECK-NEXT:    i64.xor $push5=, $pop4, $pop2
+; CHECK-NEXT:    i64.or $push9=, $pop8, $pop5
+; CHECK-NEXT:    i64.eqz $push10=, $pop9
+; CHECK-NEXT:    return $pop10
+  %cmp_16 = call i32 @memcmp(ptr %a, ptr %b, i32 16)
+  %res = icmp eq i32 %cmp_16, 0
+  ret i1 %res
+}
+
+
+
+
----------------
lukel97 wrote:

Nit some extra newlines here 
```suggestion
```

https://github.com/llvm/llvm-project/pull/148298