[InstCombine] Add tests for deducing constants based on condition in …

…select; NFC

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D148180

llvm/test/Transforms/InstCombine/binop-select.ll

@@ -5,6 +5,7 @@ declare void @use(i32)
 declare void @use_f32(float)
 declare void @use_v2f16(<2 x half>)
 declare void @use_v2i8(<2 x i8>)
+declare i32 @llvm.sadd.sat.i32(i32, i32)
 
 define i32 @test1(i1 %c, i32 %x, i32 %y) {
 ; CHECK-LABEL: @test1(
@@ -69,6 +70,45 @@ define i32 @test5(i1 %c, i32 %x, i32 %y) {
   ret i32 %add
 }
 
+define i32 @test_sub_deduce_true(i32 %x, i32 %y) {
+; CHECK-LABEL: @test_sub_deduce_true(
+; CHECK-NEXT:    [[C:%.*]] = icmp eq i32 [[X:%.*]], 9
+; CHECK-NEXT:    [[COND:%.*]] = select i1 [[C]], i32 6, i32 [[Y:%.*]]
+; CHECK-NEXT:    [[SUB:%.*]] = call i32 @llvm.sadd.sat.i32(i32 [[X]], i32 [[COND]])
+; CHECK-NEXT:    ret i32 [[SUB]]
+;
+  %c = icmp eq i32 %x, 9
+  %cond = select i1 %c, i32 6, i32 %y
+  %sub = call i32 @llvm.sadd.sat.i32(i32 %x, i32 %cond)
+  ret i32 %sub
+}
+
+define i32 @test_sub_deduce_true_no_const_fold(i32 %x, i32 %y) {
+; CHECK-LABEL: @test_sub_deduce_true_no_const_fold(
+; CHECK-NEXT:    [[C:%.*]] = icmp eq i32 [[X:%.*]], 9
+; CHECK-NEXT:    [[COND:%.*]] = select i1 [[C]], i32 [[Y:%.*]], i32 6
+; CHECK-NEXT:    [[SUB:%.*]] = call i32 @llvm.sadd.sat.i32(i32 [[X]], i32 [[COND]])
+; CHECK-NEXT:    ret i32 [[SUB]]
+;
+  %c = icmp eq i32 %x, 9
+  %cond = select i1 %c, i32 %y, i32 6
+  %sub = call i32 @llvm.sadd.sat.i32(i32 %x, i32 %cond)
+  ret i32 %sub
+}
+
+define i32 @test_sub_deduce_false(i32 %x, i32 %y) {
+; CHECK-LABEL: @test_sub_deduce_false(
+; CHECK-NEXT:    [[C_NOT:%.*]] = icmp eq i32 [[X:%.*]], 9
+; CHECK-NEXT:    [[COND:%.*]] = select i1 [[C_NOT]], i32 7, i32 [[Y:%.*]]
+; CHECK-NEXT:    [[SUB:%.*]] = call i32 @llvm.sadd.sat.i32(i32 [[X]], i32 [[COND]])
+; CHECK-NEXT:    ret i32 [[SUB]]
+;
+  %c = icmp ne i32 %x, 9
+  %cond = select i1 %c, i32 %y, i32 7
+  %sub = call i32 @llvm.sadd.sat.i32(i32 %x, i32 %cond)
+  ret i32 %sub
+}
+
 define i32 @test6(i1 %c, i32 %x, i32 %y) {
 ; CHECK-LABEL: @test6(
 ; CHECK-NEXT:    [[COND:%.*]] = select i1 [[C:%.*]], i32 7, i32 [[X:%.*]]