Let `rvalue_creates_operand` return true for *all* `Rvalue::Aggregate`s

Inspired by <https://github.com/rust-lang/rust/pull/138759#discussion_r2156375342> where I noticed that we were nearly at this point, plus the comments I was writing in 143410 that reminded me a type-dependent `true` is fine.

This PR splits the `OperandRef::builder` logic out to a separate type, with the updates needed to handle SIMD as well.  In doing so, that makes the existing `Aggregate` path in `codegen_rvalue_operand` capable of handing SIMD values just fine.

As a result, we no longer need to do layout calculations for aggregate result types when running the analysis to determine which things can be SSA in codegen.

1 files changed, 106 insertions, 0 deletions

diff --git a/tests/codegen/simd/aggregate-simd.rs b/tests/codegen/simd/aggregate-simd.rs
new file mode 100644
index 00000000000..065e429a4c7
--- /dev/null
+++ b/tests/codegen/simd/aggregate-simd.rs
@@ -0,0 +1,106 @@
+//@ compile-flags: -C opt-level=3 -C no-prepopulate-passes
+//@ only-64bit
+
+#![feature(core_intrinsics, repr_simd)]
+#![no_std]
+#![crate_type = "lib"]
+
+use core::intrinsics::simd::{simd_add, simd_extract};
+
+#[repr(simd)]
+#[derive(Clone, Copy)]
+pub struct Simd<T, const N: usize>([T; N]);
+
+#[repr(simd, packed)]
+#[derive(Clone, Copy)]
+pub struct PackedSimd<T, const N: usize>([T; N]);
+
+#[repr(transparent)]
+pub struct Transparent<T>(T);
+
+// These tests don't actually care about the add/extract, but it ensures the
+// aggregated temporaries are only used in potentially-SSA ways.
+
+#[no_mangle]
+pub fn simd_aggregate_pot(x: [u32; 4], y: [u32; 4]) -> u32 {
+    // CHECK-LABEL: simd_aggregate_pot
+    // CHECK: %a = load <4 x i32>, ptr %x, align 4
+    // CHECK: %b = load <4 x i32>, ptr %y, align 4
+    // CHECK: add <4 x i32> %a, %b
+
+    unsafe {
+        let a = Simd(x);
+        let b = Simd(y);
+        let c = simd_add(a, b);
+        simd_extract(c, 1)
+    }
+}
+
+#[no_mangle]
+pub fn simd_aggregate_npot(x: [u32; 7], y: [u32; 7]) -> u32 {
+    // CHECK-LABEL: simd_aggregate_npot
+    // CHECK: %a = load <7 x i32>, ptr %x, align 4
+    // CHECK: %b = load <7 x i32>, ptr %y, align 4
+    // CHECK: add <7 x i32> %a, %b
+
+    unsafe {
+        let a = Simd(x);
+        let b = Simd(y);
+        let c = simd_add(a, b);
+        simd_extract(c, 1)
+    }
+}
+
+#[no_mangle]
+pub fn packed_simd_aggregate_pot(x: [u32; 4], y: [u32; 4]) -> u32 {
+    // CHECK-LABEL: packed_simd_aggregate_pot
+    // CHECK: %a = load <4 x i32>, ptr %x, align 4
+    // CHECK: %b = load <4 x i32>, ptr %y, align 4
+    // CHECK: add <4 x i32> %a, %b
+
+    unsafe {
+        let a = PackedSimd(x);
+        let b = PackedSimd(y);
+        let c = simd_add(a, b);
+        simd_extract(c, 1)
+    }
+}
+
+#[no_mangle]
+pub fn packed_simd_aggregate_npot(x: [u32; 7], y: [u32; 7]) -> u32 {
+    // CHECK-LABEL: packed_simd_aggregate_npot
+    // CHECK: %b = alloca [28 x i8], align 4
+    // CHECK: %a = alloca [28 x i8], align 4
+    // CHECK: call void @llvm.memcpy.p0.p0.i64(ptr align 4 %a, ptr align 4 %x, i64 28, i1 false)
+    // CHECK: call void @llvm.memcpy.p0.p0.i64(ptr align 4 %b, ptr align 4 %y, i64 28, i1 false)
+    // CHECK: %[[TEMPA:.+]] = load <7 x i32>, ptr %a, align 4
+    // CHECK: %[[TEMPB:.+]] = load <7 x i32>, ptr %b, align 4
+    // CHECK: add <7 x i32> %[[TEMPA]], %[[TEMPB]]
+
+    unsafe {
+        let a = PackedSimd(x);
+        let b = PackedSimd(y);
+        let c = simd_add(a, b);
+        simd_extract(c, 1)
+    }
+}
+
+#[no_mangle]
+pub fn transparent_simd_aggregate(x: [u32; 4]) -> u32 {
+    // The transparent wrapper can just use the same SSA value as its field.
+    // No extra processing or spilling needed.
+
+    // CHECK-LABEL: transparent_simd_aggregate
+    // CHECK-NOT: alloca
+    // CHECK: %[[RET:.+]] = alloca [4 x i8]
+    // CHECK-NOT: alloca
+    // CHECK: %a = load <4 x i32>, ptr %x, align 4
+    // CHECK: %[[TEMP:.+]] = extractelement <4 x i32> %a, i32 1
+    // CHECK: store i32 %[[TEMP]], ptr %[[RET]]
+
+    unsafe {
+        let a = Simd(x);
+        let b = Transparent(a);
+        simd_extract(b.0, 1)
+    }
+}