Revert changes and replace undef with poison

Author: leewei05

llvm/test/Transforms/SCCP/2004-12-10-UndefBranchBug.ll

@@ -1,13 +1,14 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt < %s -passes=sccp -S | FileCheck %s
 
-define i32 @foo(i1 %arg) {
+; Branch on poison is UB, so the T block is never executed, and we can return
+; undef (IPSCCP would replace the block with unreachable).
+
+define i32 @foo() {
 ; CHECK-LABEL: @foo(
-; CHECK-NEXT:    br i1 [[ARG:%.*]], label [[T:%.*]], label [[T]]
-; CHECK:       T:
-; CHECK-NEXT:    ret i32 1
+; CHECK-NEXT:    unreachable
 ;
-  br i1 %arg, label %T, label %T
+  br i1 poison, label %T, label %T
 T:
   %X = add i32 0, 1
   ret i32 %X

llvm/test/Transforms/SCCP/return-zapped.ll

@@ -1,41 +1,37 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --function-signature
 ; RUN: opt < %s -S -passes=ipsccp | FileCheck %s
 
-define void @test1(i1 %arg) {
-; CHECK-LABEL: define {{[^@]+}}@test1
-; CHECK-SAME: (i1 [[ARG:%.*]]) {
+; testf() performs an unconditional branch on poison, as such the testf() return
+; value used in test1() will remain "unknown" and the following branch on it
+; replaced by unreachable. This is fine, as the call to testf() will already
+; trigger undefined behavior.
+define void @test1() {
+; CHECK-LABEL: define {{[^@]+}}@test1() {
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    br label [[IF_THEN:%.*]]
 ; CHECK:       if.then:
-; CHECK-NEXT:    [[CALL:%.*]] = call i1 @testf(i1 [[ARG]])
-; CHECK-NEXT:    br label [[IF_END:%.*]]
-; CHECK:       if.end:
-; CHECK-NEXT:    ret void
+; CHECK-NEXT:    [[CALL:%.*]] = call i1 @testf()
+; CHECK-NEXT:    unreachable
 ;
 entry:
   br label %if.then
 if.then:                                          ; preds = %entry, %if.then
   %foo = phi i32 [ 0, %entry], [ %next, %if.then]
   %next = add i32 %foo, 1
-  %call = call i1 @testf(i1 %arg)
+  %call = call i1 @testf()
   br i1 %call, label %if.end, label %if.then
 
 if.end:                                           ; preds = %if.then, %entry
   ret void
 }
 
-define internal i1 @testf(i1 %arg) {
-; CHECK-LABEL: define {{[^@]+}}@testf
-; CHECK-SAME: (i1 [[ARG:%.*]]) {
+define internal i1 @testf() {
+; CHECK-LABEL: define {{[^@]+}}@testf() {
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    br i1 [[ARG]], label [[IF_THEN1:%.*]], label [[IF_END3:%.*]]
-; CHECK:       if.then1:
-; CHECK-NEXT:    br label [[IF_END3]]
-; CHECK:       if.end3:
-; CHECK-NEXT:    ret i1 true
+; CHECK-NEXT:    unreachable
 ;
 entry:
-  br i1 %arg, label %if.then1, label %if.end3
+  br i1 poison, label %if.then1, label %if.end3
 
 if.then1:                                         ; preds = %if.end
   br label %if.end3
@@ -51,7 +47,7 @@ define i1 @test2() {
 ; CHECK-NEXT:    br label [[IF_END:%.*]]
 ; CHECK:       if.end:
 ; CHECK-NEXT:    [[CALL2:%.*]] = call i1 @testf()
-; CHECK-NEXT:    ret i1 [[CALL2]]
+; CHECK-NEXT:    ret i1 undef
 ;
 entry:
   br label %if.end

llvm/test/Transforms/SCCP/solve-after-each-resolving-undefs-for-function.ll

@@ -1,23 +1,22 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
 ; RUN: opt < %s -passes=ipsccp -S | FileCheck %s
 
-define internal i32 @testf(i1 %c, i1 %arg) {
-; CHECK-LABEL: define internal range(i32 10, 12) i32 @testf(
-; CHECK-SAME: i1 [[C:%.*]], i1 [[ARG:%.*]]) {
+;
+define internal i32 @testf(i1 %c) {
+; CHECK-LABEL: define internal i32 @testf(
+; CHECK-SAME: i1 [[C:%.*]]) {
 ; CHECK-NEXT:  [[ENTRY:.*:]]
 ; CHECK-NEXT:    br i1 [[C]], label %[[IF_COND:.*]], label %[[IF_END:.*]]
 ; CHECK:       [[IF_COND]]:
-; CHECK-NEXT:    br i1 [[ARG]], label %[[IF_THEN:.*]], label %[[IF_END]]
-; CHECK:       [[IF_THEN]]:
-; CHECK-NEXT:    ret i32 11
+; CHECK-NEXT:    unreachable
 ; CHECK:       [[IF_END]]:
-; CHECK-NEXT:    ret i32 10
+; CHECK-NEXT:    ret i32 poison
 ;
 entry:
   br i1 %c, label %if.cond, label %if.end
 
 if.cond:
-  br i1 %arg, label %if.then, label %if.end
+  br i1 poison, label %if.then, label %if.end
 
 if.then:                                          ; preds = %entry, %if.then
   ret i32 11
@@ -27,25 +26,22 @@ if.end:                                          ; preds = %if.then1, %entry
 }
 
 ;
-define internal i32 @test1(i1 %c, i1 %arg) {
-; CHECK-LABEL: define internal range(i32 0, 100) i32 @test1(
-; CHECK-SAME: i1 [[C:%.*]], i1 [[ARG:%.*]]) {
+define internal i32 @test1(i1 %c) {
+; CHECK-LABEL: define internal i32 @test1(
+; CHECK-SAME: i1 [[C:%.*]]) {
 ; CHECK-NEXT:  [[ENTRY:.*:]]
 ; CHECK-NEXT:    br label %[[IF_THEN:.*]]
 ; CHECK:       [[IF_THEN]]:
-; CHECK-NEXT:    [[CALL:%.*]] = call i32 @testf(i1 [[C]], i1 [[ARG]])
-; CHECK-NEXT:    [[RES:%.*]] = icmp eq i32 [[CALL]], 10
-; CHECK-NEXT:    br i1 [[RES]], label %[[RET1:.*]], label %[[RET2:.*]]
+; CHECK-NEXT:    [[CALL:%.*]] = call i32 @testf(i1 [[C]])
+; CHECK-NEXT:    br label %[[RET1:.*]]
 ; CHECK:       [[RET1]]:
-; CHECK-NEXT:    ret i32 99
-; CHECK:       [[RET2]]:
-; CHECK-NEXT:    ret i32 0
+; CHECK-NEXT:    ret i32 poison
 ;
 entry:
   br label %if.then
 
 if.then:                                          ; preds = %entry, %if.then
-  %call = call i32 @testf(i1 %c, i1 %arg)
+  %call = call i32 @testf(i1 %c)
   %res = icmp eq i32 %call, 10
   br i1 %res, label %ret1, label %ret2
 
@@ -61,7 +57,7 @@ define i32 @main(i1 %c) {
 ; CHECK-LABEL: define i32 @main(
 ; CHECK-SAME: i1 [[C:%.*]]) {
 ; CHECK-NEXT:    [[RES:%.*]] = call i32 @test1(i1 [[C]])
-; CHECK-NEXT:    ret i32 [[RES]]
+; CHECK-NEXT:    ret i32 99
 ;
   %res = call i32 @test1(i1 %c)
   ret i32 %res