[PATCH] D22413: [ValueTracking] Teach isSafeToSpeculativelyExecute() about the speculatable attribute
Tom Stellard via llvm-commits
llvm-commits at lists.llvm.org
Fri Jul 15 13:38:28 PDT 2016
tstellarAMD updated this revision to Diff 64190.
tstellarAMD added a comment.
Address some review comments.
https://reviews.llvm.org/D22413
Files:
lib/Analysis/ValueTracking.cpp
test/Transforms/SimplifyCFG/speculate-call.ll
Index: test/Transforms/SimplifyCFG/speculate-call.ll
===================================================================
--- /dev/null
+++ test/Transforms/SimplifyCFG/speculate-call.ll
@@ -0,0 +1,23 @@
+; RUN: opt -S -simplifycfg < %s | FileCheck %s
+
+; CHECK-LABEL: @speculatable_attribute
+; CHECK: select
+define i32 @speculatable_attribute(i32 %a) {
+entry:
+ %c = icmp sgt i32 %a, 64
+ br i1 %c, label %end, label %if
+
+if:
+ %val = call i32 @func() #0
+ br label %end
+
+end:
+ %ret = phi i32 [%val, %if], [0, %entry]
+ ret i32 %ret
+}
+
+define i32 @func() #0 {
+ ret i32 1
+}
+attributes #0 = { nounwind readnone speculatable }
+
Index: lib/Analysis/ValueTracking.cpp
===================================================================
--- lib/Analysis/ValueTracking.cpp
+++ lib/Analysis/ValueTracking.cpp
@@ -3118,12 +3118,18 @@
LI->getAlignment(), DL, CtxI, DT);
}
case Instruction::Call: {
+ auto *CI = cast<const CallInst>(Inst);
+ const Function *Callee = CI->getCalledFunction();
+ if (Callee && Callee->isSpeculatable())
+ return true;
if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
switch (II->getIntrinsicID()) {
// These synthetic intrinsics have no side-effects and just mark
// information about their operands.
// FIXME: There are other no-op synthetic instructions that potentially
// should be considered at least *safe* to speculate...
+ // FIXME: The speculatable attribute should be added to all these
+ // intrinsics and this case statement should be removed.
case Intrinsic::dbg_declare:
case Intrinsic::dbg_value:
return true;
-------------- next part --------------
A non-text attachment was scrubbed...
Name: D22413.64190.patch
Type: text/x-patch
Size: 1721 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20160715/236c64fa/attachment.bin>
More information about the llvm-commits
mailing list