[clang] Fix codegen of consteval functions returning an empty class, and related issues (PR #93115)

[Eli Friedman via cfe-commits]

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@@ -48,10 +48,13 @@ uint8x16x4_t test_vld4q_u8(const uint8_t *addr)
 
 // CHECK-LABEL: @test_vst2q_u32(
 // CHECK-NEXT:  entry:
-// CHECK-NEXT:    [[VALUE_COERCE_FCA_0_0_EXTRACT:%.*]] = extractvalue [[STRUCT_UINT32X4X2_T:%.*]] [[VALUE_COERCE:%.*]], 0, 0
-// CHECK-NEXT:    [[VALUE_COERCE_FCA_0_1_EXTRACT:%.*]] = extractvalue [[STRUCT_UINT32X4X2_T]] [[VALUE_COERCE]], 0, 1
-// CHECK-NEXT:    call void @llvm.arm.mve.vst2q.p0.v4i32(ptr [[ADDR:%.*]], <4 x i32> [[VALUE_COERCE_FCA_0_0_EXTRACT]], <4 x i32> [[VALUE_COERCE_FCA_0_1_EXTRACT]], i32 0)
-// CHECK-NEXT:    call void @llvm.arm.mve.vst2q.p0.v4i32(ptr [[ADDR]], <4 x i32> [[VALUE_COERCE_FCA_0_0_EXTRACT]], <4 x i32> [[VALUE_COERCE_FCA_0_1_EXTRACT]], i32 1)
+// CHECK-NEXT:    [[TMP0:%.*]] = extractvalue [[STRUCT_UINT32X4X2_T:%.*]] [[VALUE_COERCE:%.*]], 0
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efriedma-quic wrote:

Apparently I've stumbled over some limitation of instcombine.

https://github.com/llvm/llvm-project/pull/93115