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

This patch canonicalizes `extractvalue (select Cond, TV, FV)` into
`select Cond, (extractvalue TV), (extractvalue FV)`. The latter form may
enable more optimizations.

Author: dtcxzyw

llvm/lib/Transforms/InstCombine/InstructionCombining.cpp

@@ -3834,6 +3834,12 @@ Instruction *InstCombinerImpl::visitExtractValueInst(ExtractValueInst &EV) {
     if (Instruction *Res = foldOpIntoPhi(EV, PN))
       return Res;
 
+  // Canonicalize extract (select Cond, TV, FV)
+  // -> select cond, (extract TV), (extract FV)
+  if (auto *SI = dyn_cast<SelectInst>(Agg))
+    if (Instruction *R = FoldOpIntoSelect(EV, SI, /*FoldWithMultiUse=*/true))
+      return R;
+
   // We could simplify extracts from other values. Note that nested extracts may
   // already be simplified implicitly by the above: extract (extract (insert) )
   // will be translated into extract ( insert ( extract ) ) first and then just

llvm/test/Transforms/InstCombine/extract-select-agg.ll

@@ -0,0 +1,83 @@
+; 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_agg(i64 %val, i1 %cond) {
+; CHECK-LABEL: define i64 @test_select_agg_constant_agg(
+; CHECK-SAME: i64 [[VAL:%.*]], i1 [[COND:%.*]]) {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[RET:%.*]] = zext i1 [[COND]] to i64
+; CHECK-NEXT:    ret i64 [[RET]]
+;
+entry:
+  %sel = select i1 %cond, { i64, i64 } {i64 1, i64 2}, { i64, i64 } {i64 0, i64 3}
+  %ret = extractvalue { i64, i64 } %sel, 0
+  ret i64 %ret
+}
+
+define void @test_select_agg_constant_agg_multiuse(i64 %val, i1 %cond) {
+; CHECK-LABEL: define void @test_select_agg_constant_agg_multiuse(
+; CHECK-SAME: i64 [[VAL:%.*]], i1 [[COND:%.*]]) {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[RET:%.*]] = zext i1 [[COND]] to i64
+; CHECK-NEXT:    call void @use(i64 [[RET]])
+; CHECK-NEXT:    [[V1:%.*]] = select i1 [[COND]], i64 2, i64 3
+; CHECK-NEXT:    call void @use(i64 [[V1]])
+; CHECK-NEXT:    ret void
+;
+entry:
+  %sel = select i1 %cond, { i64, i64 } {i64 1, i64 2}, { i64, i64 } {i64 0, i64 3}
+  %v0 = extractvalue { i64, i64 } %sel, 0
+  call void @use(i64 %v0)
+  %v1 = extractvalue { i64, i64 } %sel, 1
+  call void @use(i64 %v1)
+  ret void
+}
+
+; TODO: it can be folded to zext i1 %cond to i64
+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:    [[A:%.*]] = insertvalue { i64, i64 } { i64 1, i64 poison }, i64 [[VAL]], 1
+; CHECK-NEXT:    [[B:%.*]] = insertvalue { i64, i64 } { i64 0, i64 poison }, i64 [[VAL]], 1
+; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[COND]], { i64, i64 } [[A]], { i64, i64 } [[B]]
+; CHECK-NEXT:    [[RET:%.*]] = extractvalue { i64, i64 } [[SEL]], 0
+; 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:    [[A0:%.*]] = insertvalue { i64, i64 } poison, i64 [[V1]], 0
+; CHECK-NEXT:    [[A1:%.*]] = insertvalue { i64, i64 } [[A0]], i64 [[V2]], 1
+; CHECK-NEXT:    [[B0:%.*]] = insertvalue { i64, i64 } poison, i64 [[V3]], 0
+; CHECK-NEXT:    [[B1:%.*]] = insertvalue { i64, i64 } [[B0]], i64 [[V4]], 1
+; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[COND]], { i64, i64 } [[A1]], { i64, i64 } [[B1]]
+; CHECK-NEXT:    [[X:%.*]] = extractvalue { i64, i64 } [[SEL]], 0
+; CHECK-NEXT:    call void @use(i64 [[X]])
+; CHECK-NEXT:    [[Y:%.*]] = extractvalue { i64, i64 } [[SEL]], 1
+; 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
+}
+
+declare void @use(i64)