[InstSimplify] Simplify calls with "returned" attribute

If a call argument has the "returned" attribute, we can simplify the call to the value of that argument. The "-inst-simplify" pass already handled this for the constant integer argument case via known bits, which is invoked in SimplifyInstruction. However, non-constant (or non-int) arguments are not handled at all right now. This addresses one of the regressions from D75801. Differential Revision: https://reviews.llvm.org/D75815
llvm · Mar 9, 2020 · 45555c3 · 45555c3
1 parent a8f76e9
commit 45555c3
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Showing 9 changed files with 14 additions and 16 deletions.
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -5348,6 +5348,9 @@ Value *llvm::SimplifyCall(CallBase *Call, const SimplifyQuery &Q) {
     if (Value *Ret = simplifyIntrinsic(Call, Q))
       return Ret;
 
+  if (Value *ReturnedArg = Call->getReturnedArgOperand())
+    return ReturnedArg;
+
   if (!canConstantFoldCallTo(Call, F))
     return nullptr;
 

diff --git a/llvm/test/Analysis/ValueTracking/known-nonnull-at.ll b/llvm/test/Analysis/ValueTracking/known-nonnull-at.ll
@@ -117,7 +117,7 @@ define i1 @nonnullReturnTest(i8* nonnull %x) {
 define i1 @unknownReturnTest(i8* %x) {
 ; CHECK-LABEL: @unknownReturnTest(
 ; CHECK-NEXT:    [[X2:%.*]] = call i8* @returningPtr(i8* [[X:%.*]])
-; CHECK-NEXT:    [[NULL_CHECK:%.*]] = icmp eq i8* [[X2]], null
+; CHECK-NEXT:    [[NULL_CHECK:%.*]] = icmp eq i8* [[X]], null
 ; CHECK-NEXT:    ret i1 [[NULL_CHECK]]
 ;
   %x2 = call i8* @returningPtr(i8* %x)

diff --git a/llvm/test/Transforms/InstCombine/align-attr.ll b/llvm/test/Transforms/InstCombine/align-attr.ll
@@ -20,7 +20,7 @@ define i32 @foo2(i32* align 32 %a) #0 {
 ; CHECK-LABEL: @foo2(
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    [[V:%.*]] = call i32* @func1(i32* [[A:%.*]])
-; CHECK-NEXT:    [[TMP0:%.*]] = load i32, i32* [[V]], align 32
+; CHECK-NEXT:    [[TMP0:%.*]] = load i32, i32* [[A]], align 32
 ; CHECK-NEXT:    ret i32 [[TMP0]]
 ;
 entry:

diff --git a/llvm/test/Transforms/InstCombine/expensive-combines.ll b/llvm/test/Transforms/InstCombine/expensive-combines.ll
@@ -16,7 +16,7 @@ define void @test() {
 ;
 ; EXPENSIVE-OFF-LABEL: @test(
 ; EXPENSIVE-OFF-NEXT:    [[CALL:%.*]] = call i32 @passthru(i32 0)
-; EXPENSIVE-OFF-NEXT:    call void @sink(i32 [[CALL]])
+; EXPENSIVE-OFF-NEXT:    call void @sink(i32 0)
 ; EXPENSIVE-OFF-NEXT:    ret void
 ;
   %call = call i32 @passthru(i32 0)

diff --git a/llvm/test/Transforms/InstCombine/fortify-folding.ll b/llvm/test/Transforms/InstCombine/fortify-folding.ll
@@ -82,7 +82,7 @@ define i32 @test_not_sprintf() {
 define i8* @test_strcat() {
 ; CHECK-LABEL: @test_strcat(
 ; CHECK-NEXT:    [[STRCAT:%.*]] = call i8* @strcat(i8* nonnull dereferenceable(1) getelementptr inbounds ([60 x i8], [60 x i8]* @a, i64 0, i64 0), i8* nonnull dereferenceable(1) getelementptr inbounds ([60 x i8], [60 x i8]* @b, i64 0, i64 0))
-; CHECK-NEXT:    ret i8* [[STRCAT]]
+; CHECK-NEXT:    ret i8* getelementptr inbounds ([60 x i8], [60 x i8]* @a, i64 0, i64 0)
 ;
   %dst = getelementptr inbounds [60 x i8], [60 x i8]* @a, i32 0, i32 0
   %src = getelementptr inbounds [60 x i8], [60 x i8]* @b, i32 0, i32 0
@@ -126,7 +126,7 @@ define i64 @test_not_strlcat() {
 define i8* @test_strncat() {
 ; CHECK-LABEL: @test_strncat(
 ; CHECK-NEXT:    [[STRNCAT:%.*]] = call i8* @strncat(i8* nonnull dereferenceable(1) getelementptr inbounds ([60 x i8], [60 x i8]* @a, i64 0, i64 0), i8* nonnull dereferenceable(1) getelementptr inbounds ([60 x i8], [60 x i8]* @b, i64 0, i64 0), i64 22)
-; CHECK-NEXT:    ret i8* [[STRNCAT]]
+; CHECK-NEXT:    ret i8* getelementptr inbounds ([60 x i8], [60 x i8]* @a, i64 0, i64 0)
 ;
   %dst = getelementptr inbounds [60 x i8], [60 x i8]* @a, i32 0, i32 0
   %src = getelementptr inbounds [60 x i8], [60 x i8]* @b, i32 0, i32 0

diff --git a/llvm/test/Transforms/InstCombine/strcpy_chk-1.ll b/llvm/test/Transforms/InstCombine/strcpy_chk-1.ll
@@ -53,7 +53,7 @@ define i8* @test_simplify3() {
 define i8* @test_simplify4() {
 ; CHECK-LABEL: @test_simplify4(
 ; CHECK-NEXT:    [[STRCPY:%.*]] = call i8* @strcpy(i8* nonnull dereferenceable(1) getelementptr inbounds ([60 x i8], [60 x i8]* @a, i32 0, i32 0), i8* nonnull dereferenceable(1) getelementptr inbounds ([60 x i8], [60 x i8]* @b, i32 0, i32 0))
-; CHECK-NEXT:    ret i8* [[STRCPY]]
+; CHECK-NEXT:    ret i8* getelementptr inbounds ([60 x i8], [60 x i8]* @a, i32 0, i32 0)
 ;
   %dst = getelementptr inbounds [60 x i8], [60 x i8]* @a, i32 0, i32 0
   %src = getelementptr inbounds [60 x i8], [60 x i8]* @b, i32 0, i32 0

diff --git a/llvm/test/Transforms/InstCombine/strncpy_chk-1.ll b/llvm/test/Transforms/InstCombine/strncpy_chk-1.ll
@@ -39,7 +39,7 @@ define i8* @test_simplify2() {
 define i8* @test_simplify3() {
 ; CHECK-LABEL: @test_simplify3(
 ; CHECK-NEXT:    [[STRNCPY:%.*]] = call i8* @strncpy(i8* nonnull dereferenceable(1) getelementptr inbounds ([60 x i8], [60 x i8]* @a, i32 0, i32 0), i8* nonnull dereferenceable(1) getelementptr inbounds ([60 x i8], [60 x i8]* @b, i32 0, i32 0), i32 12)
-; CHECK-NEXT:    ret i8* [[STRNCPY]]
+; CHECK-NEXT:    ret i8* getelementptr inbounds ([60 x i8], [60 x i8]* @a, i32 0, i32 0)
 ;
   %dst = getelementptr inbounds [60 x i8], [60 x i8]* @a, i32 0, i32 0
   %src = getelementptr inbounds [60 x i8], [60 x i8]* @b, i32 0, i32 0

diff --git a/llvm/test/Transforms/InstCombine/unused-nonnull.ll b/llvm/test/Transforms/InstCombine/unused-nonnull.ll
@@ -12,13 +12,8 @@ define i32 @main(i32 %argc, i8** %argv) #0 {
 ; CHECK-SAME: (i32 [[ARGC:%.*]], i8** nocapture readnone [[ARGV:%.*]]) local_unnamed_addr #0
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    [[TMP0:%.*]] = icmp slt i32 [[ARGC]], 2
-; CHECK-NEXT:    br i1 [[TMP0]], label [[DONE:%.*]], label [[DO_WORK:%.*]]
-; CHECK:       do_work:
-; CHECK-NEXT:    [[TMP1:%.*]] = tail call i32 @compute(i8* undef, i32 [[ARGC]])
-; CHECK-NEXT:    br label [[DONE]]
-; CHECK:       done:
-; CHECK-NEXT:    [[RETVAL:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[TMP1]], [[DO_WORK]] ]
-; CHECK-NEXT:    ret i32 [[RETVAL]]
+; CHECK-NEXT:    [[SPEC_SELECT:%.*]] = select i1 [[TMP0]], i32 0, i32 [[ARGC]]
+; CHECK-NEXT:    ret i32 [[SPEC_SELECT]]
 ;
 entry:
   %0 = getelementptr inbounds i8*, i8** %argv, i32 0

diff --git a/llvm/test/Transforms/InstSimplify/call.ll b/llvm/test/Transforms/InstSimplify/call.ll
@@ -993,7 +993,7 @@ define i32 @returned_const_int_arg() {
 define i8* @returned_const_ptr_arg() {
 ; CHECK-LABEL: @returned_const_ptr_arg(
 ; CHECK-NEXT:    [[X:%.*]] = call i8* @passthru_p8(i8* null)
-; CHECK-NEXT:    ret i8* [[X]]
+; CHECK-NEXT:    ret i8* null
 ;
   %x = call i8* @passthru_p8(i8* null)
   ret i8* %x
@@ -1002,7 +1002,7 @@ define i8* @returned_const_ptr_arg() {
 define i32 @returned_var_arg(i32 %arg) {
 ; CHECK-LABEL: @returned_var_arg(
 ; CHECK-NEXT:    [[X:%.*]] = call i32 @passthru_i32(i32 [[ARG:%.*]])
-; CHECK-NEXT:    ret i32 [[X]]
+; CHECK-NEXT:    ret i32 [[ARG]]
 ;
   %x = call i32 @passthru_i32(i32 %arg)
   ret i32 %x