Remove br i1 undef from some regression tests [NFC] (llvm#115130)

As defined in LangRef, branching on `undef` is undefined behavior.
This PR aims to remove undefined behavior from tests. As UB tests break
Alive2 and may be the root cause of breaking future optimizations.

Here's an Alive2 proof for one of the examples:
https://alive2.llvm.org/ce/z/TncxhP

Author: leewei05

llvm/test/Analysis/BasicAA/phi-values-usage.ll

@@ -20,10 +20,10 @@ declare void @llvm.lifetime.end.p0(i64, ptr nocapture)
 ; This function is one where if we didn't free basicaa after memcpyopt then the
 ; usage of basicaa in instcombine would cause a segfault due to stale phi-values
 ; results being used.
-define void @fn(ptr %this, ptr %ptr) personality ptr @__gxx_personality_v0 {
+define void @fn(ptr %this, ptr %ptr, i1 %arg) personality ptr @__gxx_personality_v0 {
 entry:
   %arr = alloca [4 x i8], align 8
-  br i1 undef, label %then, label %if
+  br i1 %arg, label %then, label %if
 
 if:
   br label %then
@@ -50,15 +50,15 @@ lpad:
 ; When running instcombine after memdep, the basicaa used by instcombine uses
 ; the phivalues that memdep used. This would then cause a segfault due to
 ; instcombine deleting a phi whose values had been cached.
-define void @fn2() {
+define void @fn2(i1 %arg) {
 entry:
   %a = alloca i8, align 1
   %0 = load ptr, ptr @c, align 1
   br label %for.cond
 
 for.cond:                                         ; preds = %for.body, %entry
   %d.0 = phi ptr [ %0, %entry ], [ null, %for.body ]
-  br i1 undef, label %for.body, label %for.cond.cleanup
+  br i1 %arg, label %for.body, label %for.cond.cleanup
 
 for.body:                                         ; preds = %for.cond
   store volatile i8 undef, ptr %a, align 1

llvm/test/Analysis/BasicAA/underlying-value.ll

@@ -3,12 +3,12 @@
 
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
 
-define void @func_20() nounwind {
+define void @func_20(i1 %arg) nounwind {
 entry:
   br label %for.cond
 
 for.cond:                                         ; preds = %for.cond2, %entry
-  br i1 undef, label %for.cond2, label %for.end22
+  br i1 %arg, label %for.cond2, label %for.end22
 
 for.cond2:                                        ; preds = %for.body5, %for.cond
   br i1 false, label %for.body5, label %for.cond

llvm/test/Analysis/BlockFrequencyInfo/irreducible_loop_crash.ll

@@ -3,10 +3,10 @@
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
-define void @fn1(ptr %f) {
+define void @fn1(ptr %f, i1 %arg) {
 entry:
   %tobool7 = icmp eq i32 undef, 0
-  br i1 undef, label %if.end.12, label %for.body.5
+  br i1 %arg, label %if.end.12, label %for.body.5
 
 for.inc:
   store i32 undef, ptr %f, align 4
@@ -19,7 +19,7 @@ for.inc.9:                                        ; preds = %for.body.5
   br i1 %tobool7, label %for.inc.9.1, label %for.inc
 
 if.end.12:                                        ; preds = %if.end.12, %for.body
-  br i1 undef, label %for.end.17, label %for.inc
+  br i1 %arg, label %for.end.17, label %for.inc
 
 for.end.17:                                       ; preds = %entry
   ret void

llvm/test/Analysis/BranchProbabilityInfo/deopt-invoke.ll

@@ -8,15 +8,15 @@ declare void @cold() cold
 
 ; Even though the likeliness of 'invoke' to throw an exception is assessed as low
 ; all other paths are even less likely. Check that hot paths leads to excepion handler.
-define void @test1(i32 %0) personality ptr @"personality_function"  !prof !1 {
+define void @test1(i32 %0, i1 %arg) personality ptr @"personality_function"  !prof !1 {
 ;CHECK: edge %entry -> %unreached probability is 0x00000001 / 0x80000000 = 0.00%
 ;CHECK: edge %entry -> %invoke probability is 0x7fffffff / 0x80000000 = 100.00% [HOT edge]
 ;CHECK: edge %invoke -> %invoke.cont.unreached probability is 0x00000000 / 0x80000000 = 0.00%
 ;CHECK: edge %invoke -> %land.pad probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge]
 ;CHECK: edge %land.pad -> %exit probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge]
 
 entry:
-  br i1 undef, label %unreached, label %invoke, !prof !2
+  br i1 %arg, label %unreached, label %invoke, !prof !2
 invoke:
   invoke void @foo(i32 %0)
           to label %invoke.cont.unreached unwind label %land.pad
@@ -38,15 +38,15 @@ exit:
   ret void
 }
 
-define void @test2(i32 %0) personality ptr @"personality_function" {
+define void @test2(i32 %0, i1 %arg) personality ptr @"personality_function" {
 ;CHECK: edge %entry -> %unreached probability is 0x00000000 / 0x80000000 = 0.00%
 ;CHECK: edge %entry -> %invoke probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge]
 ;CHECK: edge %invoke -> %invoke.cont.cold probability is 0x7fff8000 / 0x80000000 = 100.00% [HOT edge]
 ;CHECK: edge %invoke -> %land.pad probability is 0x00008000 / 0x80000000 = 0.00%
 ;CHECK: edge %land.pad -> %exit probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge]
 
 entry:
-  br i1 undef, label %unreached, label %invoke
+  br i1 %arg, label %unreached, label %invoke
 invoke:
   invoke void @foo(i32 %0)
           to label %invoke.cont.cold unwind label %land.pad
@@ -68,14 +68,14 @@ exit:
   ret void
 }
 
-define void @test3(i32 %0) personality ptr @"personality_function" {
+define void @test3(i32 %0, i1 %arg) personality ptr @"personality_function" {
 ;CHECK: edge %entry -> %unreached probability is 0x00000000 / 0x80000000 = 0.00%
 ;CHECK: edge %entry -> %invoke probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge]
 ;CHECK: edge %invoke -> %invoke.cont.cold probability is 0x7fff8000 / 0x80000000 = 100.00% [HOT edge]
 ;CHECK: edge %invoke -> %land.pad probability is 0x00008000 / 0x80000000 = 0.00%
 ;CHECK: edge %land.pad -> %exit probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge]
 entry:
-  br i1 undef, label %unreached, label %invoke
+  br i1 %arg, label %unreached, label %invoke
 invoke:
   invoke void @foo(i32 %0)
           to label %invoke.cont.cold unwind label %land.pad

llvm/test/Analysis/BranchProbabilityInfo/loop.ll

@@ -523,20 +523,20 @@ declare void @cold() cold
 
 ; If loop has single exit and it leads to 'cold' block then edge leading to loop enter
 ; should be considered 'cold' as well.
-define void @test13() {
+define void @test13(i1 %arg) {
 ; CHECK: edge %entry -> %loop probability is 0x078780e3 / 0x80000000 = 5.88%
 ; CHECK: edge %entry -> %exit probability is 0x78787f1d / 0x80000000 = 94.12% [HOT edge]
 ; CHECK: edge %loop -> %loop probability is 0x7fbe1203 / 0x80000000 = 99.80% [HOT edge]
 ; CHECK: edge %loop -> %cold probability is 0x0041edfd / 0x80000000 = 0.20%
 ; CHECK: edge %cold -> %exit probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge]
 
 entry:
-  br i1 undef, label %loop, label %exit
+  br i1 %arg, label %loop, label %exit
 
 loop:
   %i.0 = phi i32 [ 0, %entry ], [ %inc, %loop ]
   %inc = add nsw i32 %i.0, 1
-  br i1 undef, label %loop, label %cold
+  br i1 %arg, label %loop, label %cold
 
 cold:
   call void @cold()
@@ -547,7 +547,7 @@ exit:
 }
 
 ; This is the same case as test13 but with additional loop 'preheader' block.
-define void @test14() {
+define void @test14(i1 %arg) {
 ; CHECK: edge %entry -> %preheader probability is 0x078780e3 / 0x80000000 = 5.88%
 ; CHECK: edge %entry -> %exit probability is 0x78787f1d / 0x80000000 = 94.12% [HOT edge]
 ; CHECK: edge %preheader -> %loop probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge]
@@ -556,15 +556,15 @@ define void @test14() {
 ; CHECK: edge %cold -> %exit probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge]
 
 entry:
-  br i1 undef, label %preheader, label %exit
+  br i1 %arg, label %preheader, label %exit
 
 preheader:
   br label %loop
 
 loop:
   %i.0 = phi i32 [ 0, %preheader ], [ %inc, %loop ]
   %inc = add nsw i32 %i.0, 1
-  br i1 undef, label %loop, label %cold
+  br i1 %arg, label %loop, label %cold
 
 cold:
   call void @cold()
@@ -576,7 +576,7 @@ exit:
 
 ; If loop has multiple low probability exits then edge leading to loop enter
 ; should be considered low probable as well.
-define void @test15() {
+define void @test15(i1 %arg) {
 ; CHECK: edge %entry -> %loop probability is 0x078780e3 / 0x80000000 = 5.88%
 ; CHECK: edge %entry -> %exit probability is 0x78787f1d / 0x80000000 = 94.12% [HOT edge]
 ; CHECK: edge %loop -> %cont probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge]
@@ -586,15 +586,15 @@ define void @test15() {
 ; CHECK: edge %cold -> %exit probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge]
 
 entry:
-  br i1 undef, label %loop, label %exit
+  br i1 %arg, label %loop, label %exit
 
 loop:
   %i.0 = phi i32 [ 0, %entry ], [ %inc, %cont ]
   %inc = add nsw i32 %i.0, 1
-  br i1 undef, label %cont, label %unreached
+  br i1 %arg, label %cont, label %unreached
 
 cont:
-  br i1 undef, label %loop, label %cold
+  br i1 %arg, label %loop, label %cold
 
 unreached:
   unreachable
@@ -609,7 +609,7 @@ exit:
 }
 
 ; This is the same case as test15 but with additional loop 'preheader' block.
-define void @test16() {
+define void @test16(i1 %arg) {
 ; CHECK: edge %entry -> %preheader probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge]
 ; CHECK: edge %preheader -> %loop probability is 0x078780e3 / 0x80000000 = 5.88%
 ; CHECK: edge %preheader -> %exit probability is 0x78787f1d / 0x80000000 = 94.12% [HOT edge]
@@ -623,15 +623,15 @@ entry:
   br label %preheader
 
 preheader:
-  br i1 undef, label %loop, label %exit
+  br i1 %arg, label %loop, label %exit
 
 loop:
   %i.0 = phi i32 [ 0, %preheader ], [ %inc, %cont ]
   %inc = add nsw i32 %i.0, 1
-  br i1 undef, label %cont, label %unreached
+  br i1 %arg, label %cont, label %unreached
 
 cont:
-  br i1 undef, label %loop, label %cold
+  br i1 %arg, label %loop, label %cold
 
 unreached:
   unreachable
@@ -649,7 +649,7 @@ declare void @abort() noreturn
 
 ; Check that 'preheader' has 50/50 probability since there is one 'normal' exit.
 ; Check that exit to 'cold' and 'noreturn' has lower probability than 'normal' exit.
-define void @test17() {
+define void @test17(i1 %arg) {
 ; CHECK: edge %entry -> %preheader probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge]
 ; CHECK: edge %preheader -> %loop probability is 0x40000000 / 0x80000000 = 50.00%
 ; CHECK: edge %preheader -> %exit probability is 0x40000000 / 0x80000000 = 50.00%
@@ -664,18 +664,18 @@ entry:
   br label %preheader
 
 preheader:
-  br i1 undef, label %loop, label %exit
+  br i1 %arg, label %loop, label %exit
 
 loop:
   %i.0 = phi i32 [ 0, %preheader ], [ %inc, %cont2 ]
   %inc = add nsw i32 %i.0, 1
-  br i1 undef, label %cont, label %noreturn
+  br i1 %arg, label %cont, label %noreturn
 
 cont:
-  br i1 undef, label %cont2, label %cold
+  br i1 %arg, label %cont2, label %cold
 
 cont2:
-  br i1 undef, label %loop, label %exit
+  br i1 %arg, label %loop, label %exit
 
 noreturn:
   call void @abort()
@@ -692,7 +692,7 @@ exit:
 
 ; This is case with two loops where one nested into another. Nested loop has
 ; low probable exit what encreases robability to take exit in the top level loop.
-define void @test18() {
+define void @test18(i1 %arg) {
 ; CHECK: edge %entry -> %top.loop probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge]
 ; CHECK: edge %top.loop -> %loop probability is 0x546cd4b7 / 0x80000000 = 65.96%
 ; CHECK: edge %top.loop -> %exit probability is 0x2b932b49 / 0x80000000 = 34.04%
@@ -705,12 +705,12 @@ entry:
 
 top.loop:
   %j.0 = phi i32 [ 0, %entry ], [ %j.inc, %cold ]
-  br i1 undef, label %loop, label %exit
+  br i1 %arg, label %loop, label %exit
 
 loop:
   %i.0 = phi i32 [ %j.0, %top.loop ], [ %inc, %loop ]
   %inc = add nsw i32 %i.0, 1
-  br i1 undef, label %loop, label %cold
+  br i1 %arg, label %loop, label %cold
 
 cold:
   call void @cold()