test: Add some basic LLVM IR tests for atomics, volatile, and allowzero.

Author: alexrp

test/llvm_ir.zig

@@ -1,5 +1,121 @@
 pub fn addCases(cases: *tests.LlvmIrContext) void {
-    _ = cases;
+    cases.addMatches("nonnull ptr load",
+        \\export fn entry(ptr: *i16) i16 {
+        \\    return ptr.*;
+        \\}
+    , &.{
+        "ptr nonnull",
+        "load i16, ptr %0",
+    }, .{});
+
+    cases.addMatches("nonnull ptr store",
+        \\export fn entry(ptr: *i16) void {
+        \\    ptr.* = 42;
+        \\}
+    , &.{
+        "ptr nonnull",
+        "store i16 42, ptr %0",
+    }, .{});
+
+    cases.addMatches("unused acquire atomic ptr load",
+        \\export fn entry(ptr: *i16) void {
+        \\    _ = @atomicLoad(i16, ptr, .acquire);
+        \\}
+    , &.{
+        "load atomic i16, ptr %0 acquire",
+    }, .{});
+
+    cases.addMatches("unused unordered atomic volatile ptr load",
+        \\export fn entry(ptr: *volatile i16) void {
+        \\    _ = @atomicLoad(i16, ptr, .unordered);
+        \\}
+    , &.{
+        "load atomic volatile i16, ptr %0 unordered",
+    }, .{});
+
+    cases.addMatches("unused volatile ptr load",
+        \\export fn entry(ptr: *volatile i16) void {
+        \\    _ = ptr.*;
+        \\}
+    , &.{
+        "load volatile i16, ptr %0",
+    }, .{});
+
+    cases.addMatches("dead volatile ptr store",
+        \\export fn entry(ptr: *volatile i16) void {
+        \\    ptr.* = 123;
+        \\    ptr.* = 321;
+        \\}
+    , &.{
+        "store volatile i16 123, ptr %0",
+        "store volatile i16 321, ptr %0",
+    }, .{});
+
+    cases.addMatches("unused volatile slice load",
+        \\export fn entry(ptr: *volatile i16) void {
+        \\    entry2(ptr[0..1]);
+        \\}
+        \\fn entry2(ptr: []volatile i16) void {
+        \\    _ = ptr[0];
+        \\}
+    , &.{
+        "load volatile i16, ptr",
+    }, .{});
+
+    cases.addMatches("dead volatile slice store",
+        \\export fn entry(ptr: *volatile i16) void {
+        \\    entry2(ptr[0..1]);
+        \\}
+        \\fn entry2(ptr: []volatile i16) void {
+        \\    ptr[0] = 123;
+        \\    ptr[0] = 321;
+        \\}
+    , &.{
+        "store volatile i16 123, ptr",
+        "store volatile i16 321, ptr",
+    }, .{});
+
+    cases.addMatches("allowzero ptr load",
+        \\export fn entry(ptr: *allowzero i16) i16 {
+        \\    return ptr.*;
+        \\}
+    , &.{
+        "null_pointer_is_valid",
+        "load i16, ptr %0",
+    }, .{});
+
+    cases.addMatches("allowzero ptr store",
+        \\export fn entry(ptr: *allowzero i16) void {
+        \\    ptr.* = 42;
+        \\}
+    , &.{
+        "null_pointer_is_valid",
+        "store i16 42, ptr %0",
+    }, .{});
+
+    cases.addMatches("allowzero slice load",
+        \\export fn entry(ptr: *allowzero i16) i16 {
+        \\    return entry2(ptr[0..1]);
+        \\}
+        \\fn entry2(ptr: []allowzero i16) i16 {
+        \\    return ptr[0];
+        \\}
+    , &.{
+        "null_pointer_is_valid",
+        "load i16, ptr",
+    }, .{});
+
+    cases.addMatches("allowzero slice store",
+        \\export fn entry(ptr: *allowzero i16) void {
+        \\    entry2(ptr[0..1]);
+        \\}
+        \\fn entry2(ptr: []allowzero i16) void {
+        \\    ptr[0] = 42;
+        \\}
+    , &.{
+        "null_pointer_is_valid",
+        "store i16 42, ptr",
+    }, .{});
 }
 
 const std = @import("std");