instcombine: Migrate isdigit optimizations

This patch migrates the isdigit optimizations from the simplify-libcalls
pass into the instcombine library call simplifier.

llvm-svn: 168578

1 files changed, 48 insertions, 0 deletions

diff --git a/llvm/test/Transforms/InstCombine/isdigit-1.ll b/llvm/test/Transforms/InstCombine/isdigit-1.ll
new file mode 100644
index 00000000000..f291296c882
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/isdigit-1.ll
@@ -0,0 +1,48 @@
+; Test that the isdigit library call simplifier works correctly.
+;
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
+
+declare i32 @isdigit(i32)
+
+; Check isdigit(c) -> (c - '0') <u 10;
+
+define i32 @test_simplify1() {
+; CHECK: @test_simplify1
+  %ret = call i32 @isdigit(i32 47)
+  ret i32 %ret
+; CHECK-NEXT: ret i32 0
+}
+
+define i32 @test_simplify2() {
+; CHECK: @test_simplify2
+  %ret = call i32 @isdigit(i32 48)
+  ret i32 %ret
+; CHECK-NEXT: ret i32 1
+}
+
+define i32 @test_simplify3() {
+; CHECK: @test_simplify3
+  %ret = call i32 @isdigit(i32 57)
+  ret i32 %ret
+; CHECK-NEXT: ret i32 1
+}
+
+define i32 @test_simplify4() {
+; CHECK: @test_simplify4
+  %ret = call i32 @isdigit(i32 58)
+  ret i32 %ret
+; CHECK-NEXT: ret i32 0
+}
+
+define i32 @test_simplify5(i32 %x) {
+; CHECK: @test_simplify5
+
+  %ret = call i32 @isdigit(i32 %x)
+; CHECK-NEXT: [[ADD:%[a-z0-9]+]] = add i32 %x, -48
+; CHECK-NEXT: [[CMP:%[a-z0-9]+]] = icmp ult i32 [[ADD]], 10
+; CHECK-NEXT: [[ZEXT:%[a-z0-9]+]] = zext i1 [[CMP]] to i32
+  ret i32 %ret
+; CHECK-NEXT: ret i32 [[ZEXT]]
+}