[PATCH] D100095: [InstCombine] Conditionally emitting nsw/nuw flags when combining two add operations
Nikita Popov via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Wed Apr 14 11:53:28 PDT 2021
This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rG29f189f90d44: [InstCombine] Conditionally emit nowrap flags when combining two adds (authored by MehrHeidar, committed by nikic).
Changed prior to commit:
https://reviews.llvm.org/D100095?vs=337505&id=337511#toc
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D100095/new/
https://reviews.llvm.org/D100095
Files:
llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
llvm/test/Transforms/InstCombine/icmp-add.ll
Index: llvm/test/Transforms/InstCombine/icmp-add.ll
===================================================================
--- llvm/test/Transforms/InstCombine/icmp-add.ll
+++ llvm/test/Transforms/InstCombine/icmp-add.ll
@@ -666,7 +666,7 @@
define i1 @without_nsw_nuw(i8 %x, i8 %y) {
; CHECK-LABEL: @without_nsw_nuw(
-; CHECK-NEXT: [[TMP1:%.*]] = add nsw i8 [[X:%.*]], 2
+; CHECK-NEXT: [[TMP1:%.*]] = add i8 [[X:%.*]], 2
; CHECK-NEXT: [[TOBOOL:%.*]] = icmp eq i8 [[TMP1]], [[Y:%.*]]
; CHECK-NEXT: ret i1 [[TOBOOL]]
;
@@ -678,7 +678,7 @@
define i1 @with_nsw_nuw(i8 %x, i8 %y) {
; CHECK-LABEL: @with_nsw_nuw(
-; CHECK-NEXT: [[TMP1:%.*]] = add nsw i8 [[X:%.*]], 2
+; CHECK-NEXT: [[TMP1:%.*]] = add nuw nsw i8 [[X:%.*]], 2
; CHECK-NEXT: [[TOBOOL:%.*]] = icmp eq i8 [[TMP1]], [[Y:%.*]]
; CHECK-NEXT: ret i1 [[TOBOOL]]
;
@@ -702,7 +702,7 @@
define i1 @with_nsw_small(i8 %x, i8 %y) {
; CHECK-LABEL: @with_nsw_small(
-; CHECK-NEXT: [[TMP1:%.*]] = add nsw i8 [[Y:%.*]], 2
+; CHECK-NEXT: [[TMP1:%.*]] = add i8 [[Y:%.*]], 2
; CHECK-NEXT: [[TOBOOL:%.*]] = icmp eq i8 [[TMP1]], [[X:%.*]]
; CHECK-NEXT: ret i1 [[TOBOOL]]
;
@@ -714,7 +714,7 @@
define i1 @with_nuw_large(i8 %x, i8 %y) {
; CHECK-LABEL: @with_nuw_large(
-; CHECK-NEXT: [[TMP1:%.*]] = add nsw i8 [[X:%.*]], 2
+; CHECK-NEXT: [[TMP1:%.*]] = add nuw i8 [[X:%.*]], 2
; CHECK-NEXT: [[TOBOOL:%.*]] = icmp eq i8 [[TMP1]], [[Y:%.*]]
; CHECK-NEXT: ret i1 [[TOBOOL]]
;
@@ -726,7 +726,7 @@
define i1 @with_nuw_small(i8 %x, i8 %y) {
; CHECK-LABEL: @with_nuw_small(
-; CHECK-NEXT: [[TMP1:%.*]] = add nsw i8 [[Y:%.*]], 2
+; CHECK-NEXT: [[TMP1:%.*]] = add i8 [[Y:%.*]], 2
; CHECK-NEXT: [[TOBOOL:%.*]] = icmp eq i8 [[TMP1]], [[X:%.*]]
; CHECK-NEXT: ret i1 [[TOBOOL]]
;
@@ -735,3 +735,15 @@
%tobool = icmp eq i8 %t2, %t1
ret i1 %tobool
}
+
+define i1 @with_nuw_large_negative(i8 %x, i8 %y) {
+; CHECK-LABEL: @with_nuw_large_negative(
+; CHECK-NEXT: [[TMP1:%.*]] = add i8 [[X:%.*]], -2
+; CHECK-NEXT: [[TOBOOL:%.*]] = icmp eq i8 [[TMP1]], [[Y:%.*]]
+; CHECK-NEXT: ret i1 [[TOBOOL]]
+;
+ %t1 = add nuw i8 %x, -37
+ %t2 = add i8 %y, -35
+ %tobool = icmp eq i8 %t2, %t1
+ ret i1 %tobool
+}
Index: llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -3917,11 +3917,15 @@
APInt AP2Abs = C2->getValue().abs();
if (AP1Abs.uge(AP2Abs)) {
ConstantInt *C3 = Builder.getInt(AP1 - AP2);
- Value *NewAdd = Builder.CreateNSWAdd(A, C3);
+ bool HasNUW = BO0->hasNoUnsignedWrap() && C3->getValue().ule(AP1);
+ bool HasNSW = BO0->hasNoSignedWrap();
+ Value *NewAdd = Builder.CreateAdd(A, C3, "", HasNUW, HasNSW);
return new ICmpInst(Pred, NewAdd, C);
} else {
ConstantInt *C3 = Builder.getInt(AP2 - AP1);
- Value *NewAdd = Builder.CreateNSWAdd(C, C3);
+ bool HasNUW = BO1->hasNoUnsignedWrap() && C3->getValue().ule(AP2);
+ bool HasNSW = BO1->hasNoSignedWrap();
+ Value *NewAdd = Builder.CreateAdd(C, C3, "", HasNUW, HasNSW);
return new ICmpInst(Pred, A, NewAdd);
}
}
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