llvm-reduce: Reduce ifuncs

[arsenm]

Summary

Treat these basically the same way as aliases.

[aeubanks]

llvm/test/tools/llvm-reduce/remove-ifunc.ll

62

mixing ptr and * will just end up using opaque pointers everywhere, so this part is pointless

[arsenm]

llvm/test/tools/llvm-reduce/remove-ifunc.ll

62

I'm constantly wondering if I should be trying to write code that bothers trying to work with typed pointers

llvm/tools/llvm-reduce/deltas/ReduceAliases.cpp

36

I'm wondering if it would be better to lower this by emitting a call to the resolver, plus the indirect call of the result

[aeubanks]

llvm/test/tools/llvm-reduce/remove-ifunc.ll

62

I wouldn't worry about it, typed pointers are deprecated and soon to be removed

llvm/tools/llvm-reduce/deltas/ReduceAliases.cpp

36

that does make more sense

[arsenm]

Reduce to indirect call

[aeubanks]

precommit bot is saying the added tests are failing

llvm/lib/Transforms/Utils/ModuleUtils.cpp

292 ↗

(On Diff #478354)

this deserves a unittest, then I'd say we don't need as many llvm-reduce-specific tests

llvm/test/tools/llvm-reduce/remove-ifunc-constantexpr.ll

1 ↗

(On Diff #478354)

not sure how useful an XFAIL test is if the verifier should fail on this anyway and I presume nobody's producing this sort of IR

should add a FIXME verifier test separately

[arsenm]

llvm/lib/Transforms/Utils/ModuleUtils.cpp

292 ↗

(On Diff #478354)

I was going to introduce a separate lowering util pass later, I guess I can do that first

llvm/test/tools/llvm-reduce/remove-ifunc-constantexpr.ll

1 ↗

(On Diff #478354)

This is a leftover, D138634 is to disallow this

[arsenm]

llvm/lib/Transforms/Utils/ModuleUtils.cpp

292 ↗

(On Diff #478354)

D139163 jumps ahead to a utility pass, and switching strategy to using a global constructor

[arsenm]

Rebase on utility pass to use new constructor lowering

[arsenm]

ping

[arsenm]

84a413ad897c0f527095d04653dcd7333de8fb77

llvm/test/tools/llvm-reduce/remove-ifunc.ll

+; RUN: llvm-reduce --abort-on-invalid-reduction --delta-passes=ifuncs --test FileCheck --test-arg --check-prefixes=CHECK-INTERESTINGNESS --test-arg %s --test-arg --input-file %s -o %t
+; RUN: FileCheck --check-prefixes=CHECK-FINAL --input-file=%t %s
+
+; CHECK-INTERESTINGNESS: @ifunc1 = ifunc
+
+; CHECK-FINAL: @ifunc1 = ifunc void (), ptr @fn1
+@ifunc1 = ifunc void (), ptr @fn1
+@ifunc2 = ifunc void (), ptr @fn1
+
+; CHECK-INTERESTINGNESS: @ifunc3 =
+; CHECK-FINAL: @ifunc3 = ifunc i32 (double), ptr @fn2
+@ifunc3 = ifunc i32 (double), ptr @fn2
+@ifunc4 = ifunc float (i64), ptr @fn2
+
+
+; Make sure the hidden is preserved
+; CHECK-INTERESTINGNESS: @ifunc5 =
+; CHECK-FINAL: @ifunc5 = hidden ifunc i32 (double), ptr @fn3
+@ifunc5 = hidden ifunc i32 (double), ptr @fn3
+@ifunc6 = ifunc float (i64), ptr @fn4
+
+
+; Test ifunc to alias
+; CHECK-INTERESTINGNESS: @ifunc7 =
+; CHECK-FINAL: @ifunc7 = ifunc float (i64), ptr @ifunc_alias
+; CHECK-NOT: @ifunc8
+@ifunc_alias = alias void (), ptr @aliasee
+@ifunc7 = ifunc float (i64), ptr @ifunc_alias
+@ifunc8 = ifunc float (i64), ptr @ifunc_alias
+
+define void @fn1() {
+  ret void
+}
+
+define i32 @fn2(double %arg) {
+  ret i32 0
+}
+
+define i32 @fn3(double %arg) {
+  ret i32 1
+}
+
+
+; Test call to removed ifunc
+
+; CHECK-INTERESTINGNESS-LABEL: define float @fn4(
+; CHECK-INTERESTINGNESS: call float
+; CHECK-FINAL: define float @fn4(i64 %arg) {
+; CHECK-FINAL: %call = call float @fn4(i64 %arg)
+define float @fn4(i64 %arg) {
+  %call = call float @ifunc6(i64 %arg)
+  ret float %call
+}
+
+; Test call to removed bitcasted ifunc
+
+; CHECK-INTERESTINGNESS-LABEL: define i32 @fn5(
+; CHECK-INTERESTINGNESS: call i32
+; CHECK-FINAL: define i32 @fn5(double %arg) {
+; CHECK-FINAL: %call = call i32 @fn4(double %arg)
+define i32 @fn5(double %arg) {
+  %call = call i32 bitcast (float(i64)* @ifunc6 to float(i64)*)(double %arg)
+  ret i32 %call
+}
+
+; CHECK-INTERESTINGNESS: define void @aliasee()
+define void @aliasee() {
+  ret void
+}
+
+; CHECK-FINAL-LABEL: define float @call_ifunc_aliasee(
+; CHECK-FINAL: %call = call float @ifunc_alias(i64 %arg)
+define float @call_ifunc_aliasee(i64 %arg) {
+  %call = call float @ifunc8(i64 %arg)
+  ret float %call
+}

llvm/tools/llvm-reduce/DeltaManager.cpp

 
 #define DELTA_PASSES                                                           \
   do {                                                                         \
     DELTA_PASS("strip-debug-info", stripDebugInfoDeltaPass)                    \
     DELTA_PASS("functions", reduceFunctionsDeltaPass)                          \
     DELTA_PASS("function-bodies", reduceFunctionBodiesDeltaPass)               \
     DELTA_PASS("special-globals", reduceSpecialGlobalsDeltaPass)               \
     DELTA_PASS("aliases", reduceAliasesDeltaPass)                              \
+    DELTA_PASS("ifuncs", reduceIFuncsDeltaPass)                                \
     DELTA_PASS("simplify-conditionals-true", reduceConditionalsTrueDeltaPass)  \
     DELTA_PASS("simplify-conditionals-false", reduceConditionalsFalseDeltaPass)\
     DELTA_PASS("unreachable-basic-blocks", reduceUnreachableBasicBlocksDeltaPass) \
     DELTA_PASS("basic-blocks", reduceBasicBlocksDeltaPass)                     \
     DELTA_PASS("simplify-cfg", reduceUsingSimplifyCFGDeltaPass)                \
     DELTA_PASS("global-values", reduceGlobalValuesDeltaPass)                   \
     DELTA_PASS("global-objects", reduceGlobalObjectsDeltaPass)                 \
     DELTA_PASS("global-initializers", reduceGlobalsInitializersDeltaPass)      \

llvm/tools/llvm-reduce/deltas/ReduceAliases.h

 
 #ifndef LLVM_TOOLS_LLVM_REDUCE_DELTAS_REDUCEALIASES_H
 #define LLVM_TOOLS_LLVM_REDUCE_DELTAS_REDUCEALIASES_H
 
 #include "Delta.h"
 
 namespace llvm {
 void reduceAliasesDeltaPass(TestRunner &Test);
+void reduceIFuncsDeltaPass(TestRunner &Test);
 } // namespace llvm
 
 #endif

llvm/tools/llvm-reduce/deltas/ReduceAliases.cpp

static void extractAliasesFromModule(Oracle &O, Module &Program) {
   for (auto &GA : make_early_inc_range(Program.aliases())) {
     if (!O.shouldKeep()) {
       GA.replaceAllUsesWith(GA.getAliasee());
       GA.eraseFromParent();
     }
   }
 }
 
+static void extractIFuncsFromModule(Oracle &O, Module &Program) {
+  for (GlobalIFunc &GI : make_early_inc_range(Program.ifuncs())) {
+    if (!O.shouldKeep()) {
+      Constant *Resolver = GI.getResolver();
+      GI.replaceAllUsesWith(Resolver);
+      GI.eraseFromParent();
+    }
+  }
+}
+
 void llvm::reduceAliasesDeltaPass(TestRunner &Test) {
   runDeltaPass(Test, extractAliasesFromModule, "Reducing Aliases");
 }
+
+void llvm::reduceIFuncsDeltaPass(TestRunner &Test) {
+  runDeltaPass(Test, extractIFuncsFromModule, "Reducing Ifuncs");
+}