[ADCE] Add code to remove dead branches

Summary: This is last in of a series of patches to evolve ADCE.cpp to support removing of unnecessary control flow. This patch adds the code to update the control and data flow graphs to remove the dead control flow. Also update unit tests to test the capability to remove dead, may-be-infinite loop which is enabled by the switch -adce-remove-loops. Previous patches: D23824 [ADCE] Add handling of PHI nodes when removing control flow D23559 [ADCE] Add control dependence computation D23225 [ADCE] Modify data structures to support removing control flow D23065 [ADCE] Refactor anticipating new functionality (NFC) D23102 [ADCE] Refactoring for new functionality (NFC) Reviewers: dberlin, majnemer, nadav, mehdi_amini Subscribers: llvm-commits, david2050, freik, twoh Differential Revision: https://reviews.llvm.org/D24918 llvm-svn: 289548
llvm · Dec 13, 2016 · ebcf916 · ebcf916
1 parent 1647f38
commit ebcf916
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Showing 18 changed files with 328 additions and 61 deletions.
diff --git a/llvm/lib/Transforms/Scalar/ADCE.cpp b/llvm/lib/Transforms/Scalar/ADCE.cpp
diff --git a/llvm/test/Transforms/ADCE/2002-05-23-ZeroArgPHITest.ll b/llvm/test/Transforms/ADCE/2002-05-23-ZeroArgPHITest.ll
@@ -4,7 +4,8 @@
 ; removed even though there were uses still around.  Now the uses are filled
 ; in with a dummy value before the PHI is deleted.
 ;
-; RUN: opt < %s -adce
+; RUN: opt < %s -S -adce | grep bb1
+; RUN: opt < %s -S -adce -adce-remove-loops | FileCheck %s
 
         %node_t = type { double*, %node_t*, %node_t**, double**, double*, i32, i32 }
 
@@ -17,13 +18,15 @@ bb0:
 bb1:            ; preds = %bb0
         %reg107 = load %node_t*, %node_t** %nodelist.upgrd.1              ; <%node_t*> [#uses=2]
         %cond211 = icmp eq %node_t* %reg107, null               ; <i1> [#uses=1]
+; CHECK: br label %bb3
         br i1 %cond211, label %bb3, label %bb2
 
 bb2:            ; preds = %bb2, %bb1
         %reg109 = phi %node_t* [ %reg110, %bb2 ], [ %reg107, %bb1 ]             ; <%node_t*> [#uses=1]
         %reg212 = getelementptr %node_t, %node_t* %reg109, i64 0, i32 1          ; <%node_t**> [#uses=1]
         %reg110 = load %node_t*, %node_t** %reg212                ; <%node_t*> [#uses=2]
         %cond213 = icmp ne %node_t* %reg110, null               ; <i1> [#uses=1]
+; CHECK: br label %bb3
         br i1 %cond213, label %bb2, label %bb3
 
 bb3:            ; preds = %bb2, %bb1

diff --git a/llvm/test/Transforms/ADCE/2002-05-28-Crash-distilled.ll b/llvm/test/Transforms/ADCE/2002-05-28-Crash-distilled.ll
@@ -1,6 +1,7 @@
 ; This testcase is a distilled form of: 2002-05-28-Crash.ll
 
 ; RUN: opt < %s -adce 
+; RUN: opt < %s -adce -adce-remove-loops -S | FileCheck %s
 
 define float @test(i32 %i) {
         %F = sitofp i32 %i to float             ; <float> [#uses=1]
@@ -9,6 +10,7 @@ define float @test(i32 %i) {
 
 Loop:           ; preds = %Loop, %0
         %B = icmp ne i32 %I, 0          ; <i1> [#uses=1]
+; CHECK:   br label %Out
         br i1 %B, label %Out, label %Loop
 
 Out:            ; preds = %Loop

diff --git a/llvm/test/Transforms/ADCE/2002-05-28-Crash.ll b/llvm/test/Transforms/ADCE/2002-05-28-Crash.ll
@@ -12,6 +12,7 @@
 ;}
 ;
 ; RUN: opt < %s -adce
+; RUN: opt < %s -adce -adce-remove-loops -S | FileCheck %s
 
 define i32 @rx_bitset_empty(i32 %size, i32* %set) {
 bb1:
@@ -28,6 +29,7 @@ bb1:
         %reg124 = getelementptr i32, i32* %set, i64 %reg114-idxcast-offset.upgrd.1           ; <i32*> [#uses=1]
         %reg125 = load i32, i32* %reg124             ; <i32> [#uses=1]
         %cond232 = icmp ne i32 %reg125, 0               ; <i1> [#uses=1]
+; CHECK: br label %bb3
         br i1 %cond232, label %bb3, label %bb2
 
 bb2:            ; preds = %bb2, %bb1

diff --git a/llvm/test/Transforms/ADCE/2002-07-17-AssertionFailure.ll b/llvm/test/Transforms/ADCE/2002-07-17-AssertionFailure.ll
@@ -3,11 +3,12 @@
 ; block in this function, it would work fine, but that would be the part we 
 ; have to fix now, wouldn't it....
 ;
-; RUN: opt < %s -adce
+; RUN: opt < %s -adce -S | FileCheck %s
 
 define void @foo(i8* %reg5481) {
         %cast611 = bitcast i8* %reg5481 to i8**         ; <i8**> [#uses=1]
         %reg162 = load i8*, i8** %cast611            ; <i8*> [#uses=1]
+; CHECK-NOT: ptrtoint
         ptrtoint i8* %reg162 to i32             ; <i32>:1 [#uses=0]
         ret void
 }
diff --git a/llvm/test/Transforms/ADCE/2002-07-17-PHIAssertion.ll b/llvm/test/Transforms/ADCE/2002-07-17-PHIAssertion.ll
@@ -1,6 +1,6 @@
 ; This testcase was extracted from the gzip SPEC benchmark
 ;
-; RUN: opt < %s -adce
+; RUN: opt < %s -adce | FileCheck %s
 
 @bk = external global i32               ; <i32*> [#uses=2]
 @hufts = external global i32            ; <i32*> [#uses=1]
@@ -16,6 +16,8 @@ bb2:            ; preds = %bb6, %bb0
 bb3:            ; preds = %bb2
         br label %UnifiedExitNode
 
+; CHECK-NOT: bb4:
+; CHECK-NOT: bb5:
 bb4:            ; preds = %bb2
         %reg117 = load i32, i32* @hufts              ; <i32> [#uses=2]
         %cond241 = icmp ule i32 %reg117, %reg128                ; <i1> [#uses=1]

diff --git a/llvm/test/Transforms/ADCE/2002-07-29-Segfault.ll b/llvm/test/Transforms/ADCE/2002-07-29-Segfault.ll
@@ -1,4 +1,5 @@
 ; RUN: opt < %s -adce -disable-output
+; RUN: opt < %s -adce -disable-output -adce-remove-loops
 
 define void @test() {
         br label %BB3

diff --git a/llvm/test/Transforms/ADCE/2003-01-22-PredecessorProblem.ll b/llvm/test/Transforms/ADCE/2003-01-22-PredecessorProblem.ll
@@ -1,22 +1,27 @@
 ; Testcase reduced from 197.parser by bugpoint
 ; RUN: opt < %s -adce 
+; RUN: opt < %s -adce -adce-remove-loops -S | FileCheck %s
 
 define void @conjunction_prune() {
 ; <label>:0
         br label %bb19
 
 bb19:           ; preds = %bb23, %bb22, %0
         %reg205 = phi i8* [ null, %bb22 ], [ null, %bb23 ], [ null, %0 ]                ; <i8*> [#uses=1]
+; CHECK: br label %bb22
         br i1 false, label %bb21, label %bb22
 
 bb21:           ; preds = %bb19
         %cast455 = bitcast i8* %reg205 to i8**          ; <i8**> [#uses=0]
+; CHECK: br label %bb22
         br label %bb22
 
 bb22:           ; preds = %bb21, %bb19
+; CHECK: br label %bb23
         br i1 false, label %bb19, label %bb23
 
 bb23:           ; preds = %bb22
+; CHECK: br label %bb28
         br i1 false, label %bb19, label %bb28
 
 bb28:           ; preds = %bb23

diff --git a/llvm/test/Transforms/ADCE/2003-04-25-PHIPostDominateProblem.ll b/llvm/test/Transforms/ADCE/2003-04-25-PHIPostDominateProblem.ll
@@ -2,7 +2,8 @@
 ; entries for it's postdominator.  But I think this can only happen when the 
 ; PHI node is dead, so we just avoid patching up dead PHI nodes.
 
-; RUN: opt < %s -adce
+; RUN: opt < %s -adce                    -S | FileCheck %s
+; RUN: opt < %s -adce -adce-remove-loops -S | FileCheck %s
 
 target datalayout = "e-p:32:32"
 
@@ -15,6 +16,7 @@ loopentry:              ; preds = %endif, %entry
         br i1 false, label %no_exit, label %return
 
 no_exit:                ; preds = %loopentry
+; CHECK: br label %then
         br i1 false, label %then, label %else
 
 then:           ; preds = %no_exit

diff --git a/llvm/test/Transforms/ADCE/2003-06-11-InvalidCFG.ll b/llvm/test/Transforms/ADCE/2003-06-11-InvalidCFG.ll
@@ -1,4 +1,5 @@
 ; RUN: opt < %s -adce -disable-output
+; RUN: opt < %s -adce -adce-remove-loops -disable-output
 
 @G = external global i32*               ; <i32**> [#uses=1]
 

diff --git a/llvm/test/Transforms/ADCE/2003-06-24-BadSuccessor.ll b/llvm/test/Transforms/ADCE/2003-06-24-BadSuccessor.ll
@@ -1,4 +1,6 @@
 ; RUN: opt < %s -adce -disable-output
+; RUN: opt < %s -adce -adce-remove-loops=true -disable-output
+
 target datalayout = "e-p:32:32"
 	%struct..CppObjTypeDesc = type { i32, i16, i16 }
 	%struct..TypeToken = type { i32, i16, i16 }
@@ -30,6 +32,7 @@ loopentry.1:		; preds = %then.53, %endif.14
 	br i1 false, label %no_exit.1, label %loopentry.0
 
 no_exit.1:		; preds = %loopentry.1
+; CHECK: switch
 	switch i32 0, label %label.17 [
 		 i32 2, label %label.11
 		 i32 19, label %label.10

diff --git a/llvm/test/Transforms/ADCE/2003-06-24-BasicFunctionality.ll b/llvm/test/Transforms/ADCE/2003-06-24-BasicFunctionality.ll
@@ -1,4 +1,5 @@
-; RUN: opt < %s -adce -simplifycfg -S | not grep then:
+; RUN: opt < %s -adce -S | FileCheck %s
+; RUN: opt < %s -adce -adce-remove-loops -S | FileCheck %s
 
 define void @dead_test8(i32* %data.1, i32 %idx.1) {
 entry:
@@ -17,7 +18,9 @@ no_exit:                ; preds = %endif, %no_exit.preheader
         %i.0 = phi i32 [ %inc.1, %endif ], [ 0, %no_exit.preheader ]            ; <i32> [#uses=1]
         %tmp.12 = load i32, i32* %tmp.11             ; <i32> [#uses=1]
         %tmp.14 = sub i32 0, %tmp.12            ; <i32> [#uses=1]
+; CHECK-NOT: %tmp.161
         %tmp.161 = icmp ne i32 %k.1, %tmp.14            ; <i1> [#uses=1]
+; CHECK: br label %then
         br i1 %tmp.161, label %then, label %else
 
 then:           ; preds = %no_exit

diff --git a/llvm/test/Transforms/ADCE/2003-09-15-InfLoopCrash.ll b/llvm/test/Transforms/ADCE/2003-09-15-InfLoopCrash.ll
@@ -1,4 +1,5 @@
 ; RUN: opt < %s -adce -disable-output
+; RUN: opt < %s -adce -adce-remove-loops -disable-output
 
 define i32 @main() {
         br label %loop

diff --git a/llvm/test/Transforms/ADCE/2003-11-16-MissingPostDominanceInfo.ll b/llvm/test/Transforms/ADCE/2003-11-16-MissingPostDominanceInfo.ll
@@ -1,4 +1,6 @@
 ; RUN: opt < %s -adce -simplifycfg -S | grep call
+; RUN: opt < %s -adce -adce-remove-loops -simplifycfg -S | grep call
+
 declare void @exit(i32)
 
 define i32 @main(i32 %argc) {

diff --git a/llvm/test/Transforms/ADCE/2004-05-04-UnreachableBlock.ll b/llvm/test/Transforms/ADCE/2004-05-04-UnreachableBlock.ll
@@ -1,4 +1,5 @@
 ; RUN: opt < %s -adce -disable-output
+; RUN: opt < %s -adce -adce-remove-loops -disable-output
 
 define void @test() {
 entry:

diff --git a/llvm/test/Transforms/ADCE/2016-09-06.ll b/llvm/test/Transforms/ADCE/2016-09-06.ll
@@ -0,0 +1,55 @@
+; RUN: opt < %s -sroa -adce -adce-remove-loops -S | FileCheck %s
+; ModuleID = 'test1.bc'
+source_filename = "test1.c"
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Function Attrs: nounwind uwtable
+define i32 @foo(i32, i32, i32) #0 {
+  %4 = alloca i32, align 4
+  %5 = alloca i32, align 4
+  %6 = alloca i32, align 4
+  %7 = alloca i32, align 4
+  %8 = alloca i32, align 4
+  store i32 %0, i32* %4, align 4
+  store i32 %1, i32* %5, align 4
+  store i32 %2, i32* %6, align 4
+  store i32 0, i32* %7, align 4
+  %9 = load i32, i32* %5, align 4
+  %I10 = icmp ne i32 %9, 0
+  br i1 %I10, label %B11, label %B21
+
+B11: 
+  store i32 0, i32* %8, align 4
+  br label %B12
+
+B12:
+  %I13 = load i32, i32* %8, align 4
+  %I14 = load i32, i32* %6, align 4
+  %I15 = icmp slt i32 %I13, %I14
+; CHECK: br label %B20
+  br i1 %I15, label %B16, label %B20
+
+B16: 
+  br label %B17
+
+B17: 
+  %I18 = load i32, i32* %8, align 4
+  %I19 = add nsw i32 %I18, 1
+  store i32 %I19, i32* %8, align 4
+  br label %B12
+
+B20:
+  store i32 1, i32* %7, align 4
+  br label %B21
+
+B21: 
+  %I22 = load i32, i32* %7, align 4
+  ret i32 %I22
+}
+
+attributes #0 = { nounwind uwtable "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.ident = !{!0}
+
+!0 = !{!"clang version 4.0.0 (http://llvm.org/git/clang.git 5864a13abf4490e76ae2eb0896198e1305927df2)"}
diff --git a/llvm/test/Transforms/ADCE/basictest1.ll b/llvm/test/Transforms/ADCE/basictest1.ll
@@ -1,4 +1,6 @@
-; RUN: opt < %s -adce -simplifycfg | llvm-dis	
+; RUN: opt < %s -adce -S | FileCheck %s
+; RUN: opt < %s -adce -adce-remove-loops -S | FileCheck %s
+
 %FILE = type { i32, i8*, i8*, i8, i8, i32, i32, i32 }
 	%spec_fd_t = type { i32, i32, i32, i8* }
 @__iob = external global [20 x %FILE]		; <[20 x %FILE]*> [#uses=1]
@@ -24,6 +26,7 @@ declare void @perror(i8*)
 define i32 @spec_getc(i32 %fd) {
 	%reg109 = load i32, i32* @dbglvl		; <i32> [#uses=1]
 	%cond266 = icmp sle i32 %reg109, 4		; <i1> [#uses=1]
+; CHECKL br label %bb3
 	br i1 %cond266, label %bb3, label %bb2
 
 bb2:		; preds = %0
@@ -55,6 +58,7 @@ bb5:		; preds = %bb3
 bb6:		; preds = %bb5
 	%reg134 = load i32, i32* @dbglvl		; <i32> [#uses=1]
 	%cond271 = icmp sle i32 %reg134, 4		; <i1> [#uses=1]
+; CHECK: br label %bb8
 	br i1 %cond271, label %bb8, label %bb7
 
 bb7:		; preds = %bb6
@@ -77,6 +81,7 @@ bb9:		; preds = %bb5
 	store i32 %reg157, i32* %idx5
 	%reg163 = load i32, i32* @dbglvl		; <i32> [#uses=1]
 	%cond272 = icmp sle i32 %reg163, 4		; <i1> [#uses=1]
+; CHECK: br label %bb11
 	br i1 %cond272, label %bb11, label %bb10
 
 bb10:		; preds = %bb9

diff --git a/llvm/test/Transforms/ADCE/basictest2.ll b/llvm/test/Transforms/ADCE/basictest2.ll
@@ -1,4 +1,6 @@
-; RUN: opt < %s -adce -simplifycfg | llvm-dis
+; RUN: opt < %s -adce -disable-output
+; RUN: opt < %s -adce -adce-remove-loops -S | FileCheck %s
+
 	%FILE = type { i32, i8*, i8*, i8, i8, i32, i32, i32 }
 	%spec_fd_t = type { i32, i32, i32, i8* }
 @__iob = external global [20 x %FILE]		; <[20 x %FILE]*> [#uses=1]
@@ -24,6 +26,7 @@ declare void @perror(i8*)
 define i32 @spec_getc(i32 %fd) {
 	%reg109 = load i32, i32* @dbglvl		; <i32> [#uses=1]
 	%cond266 = icmp sle i32 %reg109, 4		; <i1> [#uses=1]
+; CHECK: br label %bb3
 	br i1 %cond266, label %bb3, label %bb2
 
 bb2:		; preds = %0
@@ -55,6 +58,7 @@ bb5:		; preds = %bb3
 bb6:		; preds = %bb5
 	%reg134 = load i32, i32* @dbglvl		; <i32> [#uses=1]
 	%cond271 = icmp sle i32 %reg134, 4		; <i1> [#uses=1]
+; CHECK: br label %bb8
 	br i1 %cond271, label %bb8, label %bb7
 
 bb7:		; preds = %bb6
@@ -77,6 +81,7 @@ bb9:		; preds = %bb5
 	store i32 %reg157, i32* %idx5
 	%reg163 = load i32, i32* @dbglvl		; <i32> [#uses=1]
 	%cond272 = icmp sle i32 %reg163, 4		; <i1> [#uses=1]
+; CHECK: br label %bb11
 	br i1 %cond272, label %bb11, label %bb10
 
 bb10:		; preds = %bb9