[InstCombine] Canonicalize extractvalue + select

Author: dtcxzyw

llvm/lib/Transforms/InstCombine/InstructionCombining.cpp

@@ -3834,6 +3834,16 @@ 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)) {
+    Value *Cond = SI->getCondition();
+    Value *TV = Builder.CreateExtractValue(SI->getTrueValue(), EV.getIndices());
+    Value *FV =
+        Builder.CreateExtractValue(SI->getFalseValue(), EV.getIndices());
+    return SelectInst::Create(Cond, TV, FV);
+  }
+
   // 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

@@ -5,10 +5,7 @@ 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:%.*]] = zext i1 [[COND]] to i64
 ; CHECK-NEXT:    ret i64 [[RET]]
 ;
 entry:
@@ -23,14 +20,9 @@ define void @test_select_agg_multiuse(i1 %cond, i64 %v1, i64 %v2, i64 %v3, i64 %
 ; 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:    [[X:%.*]] = select i1 [[COND]], i64 [[V1]], i64 [[V3]]
 ; CHECK-NEXT:    call void @use(i64 [[X]])
-; CHECK-NEXT:    [[Y:%.*]] = extractvalue { i64, i64 } [[SEL]], 1
+; CHECK-NEXT:    [[Y:%.*]] = select i1 [[COND]], i64 [[V2]], i64 [[V4]]
 ; CHECK-NEXT:    call void @use(i64 [[Y]])
 ; CHECK-NEXT:    ret void
 ;