[NFC][PhaseOrdering] Add end-to-end tests for the 'two shifts by sext' problem

We start with two separate sext's, but EarlyCSE runs before InstCombine,
so when we get them, they are a single sext, and we just ignore that.
Likewise, if we had a single sext, we don't do anything there.

llvm-svn: 373115

diff --git a/llvm/test/Transforms/PhaseOrdering/two-shifts-by-sext.ll b/llvm/test/Transforms/PhaseOrdering/two-shifts-by-sext.ll
new file mode 100644 (file)
index 0000000..4d4a30e
--- /dev/null
+++ b/llvm/test/Transforms/PhaseOrdering/two-shifts-by-sext.ll
@@ -0,0 +1,125 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -O1 -S < %s | FileCheck %s --check-prefixes=CHECK,CHECK-01
+; RUN: opt -O2 -S < %s | FileCheck %s --check-prefixes=CHECK,CHECK-02
+; RUN: opt -O3 -S < %s | FileCheck %s --check-prefixes=CHECK,CHECK-03
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; int two_shifts_by_sext(int val, char len) {
+;   return (val << len) >> len;
+; }
+;
+; int two_shifts_by_same_sext(int val, char len) {
+;   int wide_len = len;
+;   return (val << wide_len) >> wide_len;
+; }
+;
+; void use_int32(int);
+; int two_shifts_by_sext_with_extra_use(int val, char len) {
+;   use_int32(len);
+;   return (val << len) >> len;
+; }
+;
+; int two_shifts_by_same_sext_with_extra_use(int val, char len) {
+;   int wide_len = len;
+;   use_int32(wide_len);
+;   return (val << wide_len) >> wide_len;
+; }
+
+define i32 @two_shifts_by_sext(i32 %val, i8 signext %len) {
+; CHECK-LABEL: @two_shifts_by_sext(
+; CHECK-NEXT:    [[CONV:%.*]] = sext i8 [[LEN:%.*]] to i32
+; CHECK-NEXT:    [[SHL:%.*]] = shl i32 [[VAL:%.*]], [[CONV]]
+; CHECK-NEXT:    [[SHR:%.*]] = ashr i32 [[SHL]], [[CONV]]
+; CHECK-NEXT:    ret i32 [[SHR]]
+;
+  %val.addr = alloca i32, align 4
+  %len.addr = alloca i8, align 1
+  store i32 %val, i32* %val.addr, align 4
+  store i8 %len, i8* %len.addr, align 1
+  %val.reloaded = load i32, i32* %val.addr, align 4
+  %len.reloaded.0 = load i8, i8* %len.addr, align 1
+  %conv = sext i8 %len.reloaded.0 to i32
+  %shl = shl i32 %val.reloaded, %conv
+  %len.reloaded.1 = load i8, i8* %len.addr, align 1
+  %conv1 = sext i8 %len.reloaded.1 to i32
+  %shr = ashr i32 %shl, %conv1
+  ret i32 %shr
+}
+
+define i32 @two_shifts_by_same_sext(i32 %val, i8 signext %len) {
+; CHECK-LABEL: @two_shifts_by_same_sext(
+; CHECK-NEXT:    [[CONV:%.*]] = sext i8 [[LEN:%.*]] to i32
+; CHECK-NEXT:    [[SHL:%.*]] = shl i32 [[VAL:%.*]], [[CONV]]
+; CHECK-NEXT:    [[SHR:%.*]] = ashr i32 [[SHL]], [[CONV]]
+; CHECK-NEXT:    ret i32 [[SHR]]
+;
+  %val.addr = alloca i32, align 4
+  %len.addr = alloca i8, align 1
+  %wide_len = alloca i32, align 4
+  store i32 %val, i32* %val.addr, align 4
+  store i8 %len, i8* %len.addr, align 1
+  %len.reloaded.0 = load i8, i8* %len.addr, align 1
+  %conv = sext i8 %len.reloaded.0 to i32
+  store i32 %conv, i32* %wide_len, align 4
+  %val.reloaded = load i32, i32* %val.addr, align 4
+  %len.reloaded.1 = load i32, i32* %wide_len, align 4
+  %shl = shl i32 %val.reloaded, %len.reloaded.1
+  %len.reloaded.2 = load i32, i32* %wide_len, align 4
+  %shr = ashr i32 %shl, %len.reloaded.2
+  ret i32 %shr
+}
+
+define i32 @two_shifts_by_sext_with_extra_use(i32 %val, i8 signext %len) {
+; CHECK-LABEL: @two_shifts_by_sext_with_extra_use(
+; CHECK-NEXT:    [[CONV:%.*]] = sext i8 [[LEN:%.*]] to i32
+; CHECK-NEXT:    tail call void @use_int32(i32 [[CONV]])
+; CHECK-NEXT:    [[SHL:%.*]] = shl i32 [[VAL:%.*]], [[CONV]]
+; CHECK-NEXT:    [[SHR:%.*]] = ashr i32 [[SHL]], [[CONV]]
+; CHECK-NEXT:    ret i32 [[SHR]]
+;
+  %val.addr = alloca i32, align 4
+  %len.addr = alloca i8, align 1
+  store i32 %val, i32* %val.addr, align 4
+  store i8 %len, i8* %len.addr, align 1
+  %len.reloaded.0 = load i8, i8* %len.addr, align 1
+  %conv = sext i8 %len.reloaded.0 to i32
+  call void @use_int32(i32 %conv)
+  %val.reloaded = load i32, i32* %val.addr, align 4
+  %len.reloaded.1 = load i8, i8* %len.addr, align 1
+  %conv1 = sext i8 %len.reloaded.1 to i32
+  %shl = shl i32 %val.reloaded, %conv1
+  %len.reloaded.2 = load i8, i8* %len.addr, align 1
+  %conv2 = sext i8 %len.reloaded.2 to i32
+  %shr = ashr i32 %shl, %conv2
+  ret i32 %shr
+}
+
+declare void @use_int32(i32)
+
+define i32 @two_shifts_by_same_sext_with_extra_use(i32 %val, i8 signext %len) {
+; CHECK-LABEL: @two_shifts_by_same_sext_with_extra_use(
+; CHECK-NEXT:    [[CONV:%.*]] = sext i8 [[LEN:%.*]] to i32
+; CHECK-NEXT:    tail call void @use_int32(i32 [[CONV]])
+; CHECK-NEXT:    [[SHL:%.*]] = shl i32 [[VAL:%.*]], [[CONV]]
+; CHECK-NEXT:    [[SHR:%.*]] = ashr i32 [[SHL]], [[CONV]]
+; CHECK-NEXT:    ret i32 [[SHR]]
+;
+  %val.addr = alloca i32, align 4
+  %len.addr = alloca i8, align 1
+  %wide_len = alloca i32, align 4
+  store i32 %val, i32* %val.addr, align 4
+  store i8 %len, i8* %len.addr, align 1
+  %len.reloaded.0 = load i8, i8* %len.addr, align 1
+  %conv = sext i8 %len.reloaded.0 to i32
+  store i32 %conv, i32* %wide_len, align 4
+  %val.reloaded = load i32, i32* %wide_len, align 4
+  call void @use_int32(i32 %val.reloaded)
+  %len.reloaded.1 = load i32, i32* %val.addr, align 4
+  %len.reloaded.2 = load i32, i32* %wide_len, align 4
+  %shl = shl i32 %len.reloaded.1, %len.reloaded.2
+  %wide_len.reloaded = load i32, i32* %wide_len, align 4
+  %shr = ashr i32 %shl, %wide_len.reloaded
+  ret i32 %shr
+}