[NFC][InstCombine] conditional sign-extend of high-bit-extract: 'and' pat. can be...

In this pattern, all the "magic" bits that we'd add are all
high sign bits, and in the value we'd be adding to they are all unset,
not unexpectedly, so we can have an `or` there:
https://rise4fun.com/Alive/ups

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@375377 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/test/Transforms/InstCombine/conditional-variable-length-signext-after-high-bit-extract.ll b/test/Transforms/InstCombine/conditional-variable-length-signext-after-high-bit-extract.ll
index 027755641e87e2c7a2b489d0510222a8086467c9..3dc1fd244a30cf64fbca6bf29038ebc8704ed088 100644 (file)
--- a/test/Transforms/InstCombine/conditional-variable-length-signext-after-high-bit-extract.ll
+++ b/test/Transforms/InstCombine/conditional-variable-length-signext-after-high-bit-extract.ll
@@ -45,6 +45,37 @@ define i32 @t0_notrunc_add(i32 %data, i32 %nbits) {
   ret i32 %signextended
 }
 
+define i32 @t0_notrunc_or(i32 %data, i32 %nbits) {
+; CHECK-LABEL: @t0_notrunc_or(
+; CHECK-NEXT:    [[LOW_BITS_TO_SKIP:%.*]] = sub i32 32, [[NBITS:%.*]]
+; CHECK-NEXT:    [[HIGH_BITS_EXTRACTED:%.*]] = lshr i32 [[DATA:%.*]], [[LOW_BITS_TO_SKIP]]
+; CHECK-NEXT:    [[SHOULD_SIGNEXT:%.*]] = icmp slt i32 [[DATA]], 0
+; CHECK-NEXT:    [[ALL_BITS_EXCEPT_LOW_NBITS:%.*]] = shl i32 -1, [[NBITS]]
+; CHECK-NEXT:    [[MAGIC:%.*]] = select i1 [[SHOULD_SIGNEXT]], i32 [[ALL_BITS_EXCEPT_LOW_NBITS]], i32 0
+; CHECK-NEXT:    call void @use32(i32 [[LOW_BITS_TO_SKIP]])
+; CHECK-NEXT:    call void @use32(i32 [[HIGH_BITS_EXTRACTED]])
+; CHECK-NEXT:    call void @use1(i1 [[SHOULD_SIGNEXT]])
+; CHECK-NEXT:    call void @use32(i32 [[ALL_BITS_EXCEPT_LOW_NBITS]])
+; CHECK-NEXT:    call void @use32(i32 [[MAGIC]])
+; CHECK-NEXT:    [[SIGNEXTENDED:%.*]] = or i32 [[HIGH_BITS_EXTRACTED]], [[MAGIC]]
+; CHECK-NEXT:    ret i32 [[SIGNEXTENDED]]
+;
+  %low_bits_to_skip = sub i32 32, %nbits
+  %high_bits_extracted = lshr i32 %data, %low_bits_to_skip
+  %should_signext = icmp slt i32 %data, 0
+  %all_bits_except_low_nbits = shl i32 -1, %nbits
+  %magic = select i1 %should_signext, i32 %all_bits_except_low_nbits, i32 0
+
+  call void @use32(i32 %low_bits_to_skip)
+  call void @use32(i32 %high_bits_extracted)
+  call void @use1(i1 %should_signext)
+  call void @use32(i32 %all_bits_except_low_nbits)
+  call void @use32(i32 %magic)
+
+  %signextended = or i32 %high_bits_extracted, %magic
+  ret i32 %signextended
+}
+
 define i32 @t1_notrunc_sub(i32 %data, i32 %nbits) {
 ; CHECK-LABEL: @t1_notrunc_sub(
 ; CHECK-NEXT:    [[LOW_BITS_TO_SKIP:%.*]] = sub i32 32, [[NBITS:%.*]]
@@ -113,6 +144,43 @@ define i32 @t2_trunc_add(i64 %data, i32 %nbits) {
   ret i32 %signextended
 }
 
+define i32 @t2_trunc_or(i64 %data, i32 %nbits) {
+; CHECK-LABEL: @t2_trunc_or(
+; CHECK-NEXT:    [[LOW_BITS_TO_SKIP:%.*]] = sub i32 64, [[NBITS:%.*]]
+; CHECK-NEXT:    [[LOW_BITS_TO_SKIP_WIDE:%.*]] = zext i32 [[LOW_BITS_TO_SKIP]] to i64
+; CHECK-NEXT:    [[HIGH_BITS_EXTRACTED_WIDE:%.*]] = lshr i64 [[DATA:%.*]], [[LOW_BITS_TO_SKIP_WIDE]]
+; CHECK-NEXT:    [[HIGH_BITS_EXTRACTED:%.*]] = trunc i64 [[HIGH_BITS_EXTRACTED_WIDE]] to i32
+; CHECK-NEXT:    [[SHOULD_SIGNEXT:%.*]] = icmp slt i64 [[DATA]], 0
+; CHECK-NEXT:    [[ALL_BITS_EXCEPT_LOW_NBITS:%.*]] = shl i32 -1, [[NBITS]]
+; CHECK-NEXT:    [[MAGIC:%.*]] = select i1 [[SHOULD_SIGNEXT]], i32 [[ALL_BITS_EXCEPT_LOW_NBITS]], i32 0
+; CHECK-NEXT:    call void @use32(i32 [[LOW_BITS_TO_SKIP]])
+; CHECK-NEXT:    call void @use64(i64 [[LOW_BITS_TO_SKIP_WIDE]])
+; CHECK-NEXT:    call void @use64(i64 [[HIGH_BITS_EXTRACTED_WIDE]])
+; CHECK-NEXT:    call void @use32(i32 [[HIGH_BITS_EXTRACTED]])
+; CHECK-NEXT:    call void @use1(i1 [[SHOULD_SIGNEXT]])
+; CHECK-NEXT:    call void @use32(i32 [[ALL_BITS_EXCEPT_LOW_NBITS]])
+; CHECK-NEXT:    [[SIGNEXTENDED:%.*]] = or i32 [[MAGIC]], [[HIGH_BITS_EXTRACTED]]
+; CHECK-NEXT:    ret i32 [[SIGNEXTENDED]]
+;
+  %low_bits_to_skip = sub i32 64, %nbits
+  %low_bits_to_skip_wide = zext i32 %low_bits_to_skip to i64
+  %high_bits_extracted_wide = lshr i64 %data, %low_bits_to_skip_wide
+  %high_bits_extracted = trunc i64 %high_bits_extracted_wide to i32
+  %should_signext = icmp slt i64 %data, 0
+  %all_bits_except_low_nbits = shl i32 -1, %nbits
+  %magic = select i1 %should_signext, i32 %all_bits_except_low_nbits, i32 0 ; one-use
+
+  call void @use32(i32 %low_bits_to_skip)
+  call void @use64(i64 %low_bits_to_skip_wide)
+  call void @use64(i64 %high_bits_extracted_wide)
+  call void @use32(i32 %high_bits_extracted)
+  call void @use1(i1 %should_signext)
+  call void @use32(i32 %all_bits_except_low_nbits)
+
+  %signextended = or i32 %magic, %high_bits_extracted
+  ret i32 %signextended
+}
+
 define i32 @t3_trunc_sub(i64 %data, i32 %nbits) {
 ; CHECK-LABEL: @t3_trunc_sub(
 ; CHECK-NEXT:    [[LOW_BITS_TO_SKIP:%.*]] = sub i32 64, [[NBITS:%.*]]
@@ -1038,3 +1106,34 @@ define i32 @n28_sub_sext_of_magic(i32 %data, i8 %nbits) {
   %signextended = sub i32 %high_bits_extracted, %magic_wide
   ret i32 %signextended
 }
+
+define i32 @n290_or_with_wrong_magic(i32 %data, i32 %nbits) {
+; CHECK-LABEL: @n290_or_with_wrong_magic(
+; CHECK-NEXT:    [[LOW_BITS_TO_SKIP:%.*]] = sub i32 32, [[NBITS:%.*]]
+; CHECK-NEXT:    [[HIGH_BITS_EXTRACTED:%.*]] = lshr i32 [[DATA:%.*]], [[LOW_BITS_TO_SKIP]]
+; CHECK-NEXT:    [[SHOULD_SIGNEXT:%.*]] = icmp slt i32 [[DATA]], 0
+; CHECK-NEXT:    [[ALL_BITS_EXCEPT_LOW_NBITS:%.*]] = shl i32 1, [[NBITS]]
+; CHECK-NEXT:    [[MAGIC:%.*]] = select i1 [[SHOULD_SIGNEXT]], i32 [[ALL_BITS_EXCEPT_LOW_NBITS]], i32 0
+; CHECK-NEXT:    call void @use32(i32 [[LOW_BITS_TO_SKIP]])
+; CHECK-NEXT:    call void @use32(i32 [[HIGH_BITS_EXTRACTED]])
+; CHECK-NEXT:    call void @use1(i1 [[SHOULD_SIGNEXT]])
+; CHECK-NEXT:    call void @use32(i32 [[ALL_BITS_EXCEPT_LOW_NBITS]])
+; CHECK-NEXT:    call void @use32(i32 [[MAGIC]])
+; CHECK-NEXT:    [[SIGNEXTENDED:%.*]] = or i32 [[HIGH_BITS_EXTRACTED]], [[MAGIC]]
+; CHECK-NEXT:    ret i32 [[SIGNEXTENDED]]
+;
+  %low_bits_to_skip = sub i32 32, %nbits
+  %high_bits_extracted = lshr i32 %data, %low_bits_to_skip
+  %should_signext = icmp slt i32 %data, 0
+  %all_bits_except_low_nbits = shl i32 1, %nbits ; not -1
+  %magic = select i1 %should_signext, i32 %all_bits_except_low_nbits, i32 0
+
+  call void @use32(i32 %low_bits_to_skip)
+  call void @use32(i32 %high_bits_extracted)
+  call void @use1(i1 %should_signext)
+  call void @use32(i32 %all_bits_except_low_nbits)
+  call void @use32(i32 %magic)
+
+  %signextended = or i32 %high_bits_extracted, %magic
+  ret i32 %signextended
+}