[llvm] [InstCombine] Canonicalize `extractvalue + select` (PR #84686)

[via llvm-commits]

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@@ -0,0 +1,60 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
+; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+
+define i64 @test_select_agg_constant(i64 %val, i1 %cond) {
+; CHECK-LABEL: define i64 @test_select_agg_constant(
+; CHECK-SAME: i64 [[VAL:%.*]], i1 [[COND:%.*]]) {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[RET:%.*]] = zext i1 [[COND]] to i64
+; CHECK-NEXT:    ret i64 [[RET]]
+;
+entry:
+  %a = insertvalue { i64, i64 } { i64 1, i64 poison }, i64 %val, 1
+  %b = insertvalue { i64, i64 } { i64 0, i64 poison }, i64 %val, 1
+  %sel = select i1 %cond, { i64, i64 } %a, { i64, i64 } %b
+  %ret = extractvalue { i64, i64 } %sel, 0
+  ret i64 %ret
+}
+
+define void @test_select_agg_multiuse(i1 %cond, i64 %v1, i64 %v2, i64 %v3, i64 %v4) {
+; CHECK-LABEL: define void @test_select_agg_multiuse(
+; CHECK-SAME: i1 [[COND:%.*]], i64 [[V1:%.*]], i64 [[V2:%.*]], i64 [[V3:%.*]], i64 [[V4:%.*]]) {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[X:%.*]] = select i1 [[COND]], i64 [[V1]], i64 [[V3]]
+; CHECK-NEXT:    call void @use(i64 [[X]])
+; CHECK-NEXT:    [[Y:%.*]] = select i1 [[COND]], i64 [[V2]], i64 [[V4]]
+; CHECK-NEXT:    call void @use(i64 [[Y]])
+; CHECK-NEXT:    ret void
+;
+entry:
+  %a0 = insertvalue { i64, i64 } poison, i64 %v1, 0
+  %a1 = insertvalue { i64, i64 } %a0, i64 %v2, 1
+  %b0 = insertvalue { i64, i64 } poison, i64 %v3, 0
+  %b1 = insertvalue { i64, i64 } %b0, i64 %v4, 1
+  %sel = select i1 %cond, { i64, i64 } %a1, { i64, i64 } %b1
+  %x = extractvalue { i64, i64 } %sel, 0
+  call void @use(i64 %x)
+  %y = extractvalue { i64, i64 } %sel, 1
+  call void @use(i64 %y)
+  ret void
+}
+
+define i64 @test_select_agg_simplified(i1 %cond, i64 %v1, i64 %v2, i64 %v3, i64 %v4) {
+; CHECK-LABEL: define i64 @test_select_agg_simplified(
+; CHECK-SAME: i1 [[COND:%.*]], i64 [[V1:%.*]], i64 [[V2:%.*]], i64 [[V3:%.*]], i64 [[V4:%.*]]) {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[RET:%.*]] = select i1 [[COND]], i64 [[V2]], i64 0
+; CHECK-NEXT:    ret i64 [[RET]]
+;
+entry:
+  %a0 = insertvalue { i64, i64 } poison, i64 %v1, 0
+  %a1 = insertvalue { i64, i64 } %a0, i64 %v2, 1
+  %b0 = insertvalue { i64, i64 } poison, i64 %v3, 0
+  %b1 = insertvalue { i64, i64 } %b0, i64 %v4, 1
+  %sel = select i1 %cond, { i64, i64 } %a1, { i64, i64 } %b1
+  %y = extractvalue { i64, i64 } %sel, 1
+  %ret = select i1 %cond, i64 %y, i64 0
+  ret i64 %ret
+}
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goldsteinn wrote:

Can you add a test where the structs are passed in and not inserted to in the function.
It seems like you will create instructions in that case.

https://github.com/llvm/llvm-project/pull/84686