[llvm] [clang] [clang-tools-extra] [ISel] Add pattern matching for depositing subreg value (PR #75978)

[Shengchen Kan via cfe-commits]

================
@@ -0,0 +1,34 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 4
+;RUN: llc < %s -mtriple=x86_64-unknown-unknown | FileCheck %s --check-prefixes=X64
+
+define i64 @sub8(i64 noundef %res, ptr %byte) {
+; X64-LABEL: sub8:
+; X64:       # %bb.0: # %entry
+; X64-NEXT:    movq %rdi, %rax
+; X64-NEXT:    movb (%rsi), %al
+; X64-NEXT:    retq
+entry:
+  %and = and i64 %res, -256
+  %d = load i8, ptr %byte, align 1
+  %conv2 = zext i8 %d to i64
+  %or = or i64 %and, %conv2
+  ret i64 %or
+}
+
+define i64 @sub16(i64 noundef %res, ptr %byte) {
+; X64-LABEL: sub16:
+; X64:       # %bb.0: # %entry
+; X64-NEXT:    movq %rdi, %rax
+; X64-NEXT:    movw (%rsi), %ax
+; X64-NEXT:    retq
+entry:
+  %and = and i64 %res, -65536
+  %d = load i16, ptr %byte, align 1
+  %conv2 = zext i16 %d to i64
+  %or = or i64 %and, %conv2
+  ret i64 %or
+}
+
+
+
+
----------------
KanRobert wrote:

drop trailing new lines

https://github.com/llvm/llvm-project/pull/75978