[llvm] [CGP] Consider arguments and ret values in `dupRetToEnableTailCallOpts` (PR #76613)
Antonio Frighetto via llvm-commits
llvm-commits at lists.llvm.org
Tue Jan 30 13:52:52 PST 2024
https://github.com/antoniofrighetto updated https://github.com/llvm/llvm-project/pull/76613
>From 87a21891a32fad484f72ef9af26ef245b8ec3994 Mon Sep 17 00:00:00 2001
From: Antonio Frighetto <me at antoniofrighetto.com>
Date: Sat, 30 Dec 2023 00:21:12 +0100
Subject: [PATCH 1/2] [CGP] Precommit tests for PR76613 (NFC)
---
llvm/test/CodeGen/X86/tailcall-cgp-dup.ll | 144 +++++++++++++++++++++-
1 file changed, 143 insertions(+), 1 deletion(-)
diff --git a/llvm/test/CodeGen/X86/tailcall-cgp-dup.ll b/llvm/test/CodeGen/X86/tailcall-cgp-dup.ll
index 75bbae1050d61..9241693c1fc82 100644
--- a/llvm/test/CodeGen/X86/tailcall-cgp-dup.ll
+++ b/llvm/test/CodeGen/X86/tailcall-cgp-dup.ll
@@ -1,4 +1,4 @@
-; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --filter-out "cfi"
; RUN: llc < %s -mtriple=x86_64-apple-darwin | FileCheck %s
; RUN: opt -S -passes='require<profile-summary>,function(codegenprepare)' %s -mtriple=x86_64-apple-darwin -o - | FileCheck %s --check-prefix OPT
@@ -184,3 +184,145 @@ return:
%retval = phi ptr [ %ptr, %if.then ], [ %obj, %entry ]
ret ptr %retval
}
+
+define ptr @memset_tailc(ptr %ret_val, i64 %sz) {
+; CHECK-LABEL: memset_tailc:
+; CHECK: ## %bb.0: ## %entry
+; CHECK: pushq %rbx
+; CHECK: movq %rdi, %rbx
+; CHECK: testq %rdi, %rdi
+; CHECK: je LBB4_2
+; CHECK: ## %bb.1: ## %if.then
+; CHECK: movq %rsi, %rdx
+; CHECK: movq %rbx, %rdi
+; CHECK: xorl %esi, %esi
+; CHECK: callq _memset
+; CHECK: LBB4_2: ## %return
+; CHECK: movq %rbx, %rax
+; CHECK: popq %rbx
+; CHECK: retq
+entry:
+ %cmp = icmp eq ptr %ret_val, null
+ br i1 %cmp, label %return, label %if.then
+
+if.then:
+ tail call void @llvm.memset.p0.i64(ptr nonnull align 1 %ret_val, i8 0, i64 %sz, i1 false)
+ br label %return
+
+return:
+ ret ptr %ret_val
+}
+
+define ptr @memcpy_tailc(ptr %ret_val, i64 %sz, ptr %src) {
+; CHECK-LABEL: memcpy_tailc:
+; CHECK: ## %bb.0: ## %entry
+; CHECK: pushq %rbx
+; CHECK: testq %rsi, %rsi
+; CHECK: je LBB5_1
+; CHECK: ## %bb.2: ## %if.then
+; CHECK: movq %rsi, %rax
+; CHECK: movq %rdi, %rbx
+; CHECK: movq %rdx, %rsi
+; CHECK: movq %rax, %rdx
+; CHECK: callq _memcpy
+; CHECK: jmp LBB5_3
+; CHECK: LBB5_1:
+; CHECK: movq %rdx, %rbx
+; CHECK: LBB5_3: ## %return
+; CHECK: movq %rbx, %rax
+; CHECK: popq %rbx
+; CHECK: retq
+entry:
+ %cmp = icmp eq i64 %sz, 0
+ br i1 %cmp, label %return, label %if.then
+
+if.then:
+ tail call void @llvm.memcpy.p0.p0.i64(ptr align 1 %ret_val, ptr align 1 %src, i64 %sz, i1 false)
+ br label %return
+
+return:
+ %phi = phi ptr [ %ret_val, %if.then ], [ %src, %entry ]
+ ret ptr %phi
+}
+
+define ptr @strcpy_legal_and_baz_illegal(ptr %arg, i64 %sz, ptr %2) {
+; CHECK-LABEL: strcpy_legal_and_baz_illegal:
+; CHECK: ## %bb.0: ## %entry
+; CHECK: pushq %r15
+; CHECK: pushq %r14
+; CHECK: pushq %rbx
+; CHECK: movq %rdx, %r14
+; CHECK: movq %rsi, %r15
+; CHECK: movq %rdi, %rbx
+; CHECK: movq %rsi, %rdi
+; CHECK: callq _malloc
+; CHECK: testq %r15, %r15
+; CHECK: je LBB6_2
+; CHECK: ## %bb.1: ## %if.then
+; CHECK: movq %rax, %rdi
+; CHECK: movq %r14, %rsi
+; CHECK: movq %rax, %rbx
+; CHECK: callq _strcpy
+; CHECK: jmp LBB6_3
+; CHECK: LBB6_2: ## %if.else
+; CHECK: movq %rbx, %rdi
+; CHECK: movq %r14, %rsi
+; CHECK: callq _baz
+; CHECK: LBB6_3: ## %return
+; CHECK: movq %rbx, %rax
+; CHECK: popq %rbx
+; CHECK: popq %r14
+; CHECK: popq %r15
+; CHECK: retq
+entry:
+ %strcpy_ret_val = tail call noalias ptr @malloc(i64 %sz)
+ %cmp = icmp eq i64 %sz, 0
+ br i1 %cmp, label %if.else, label %if.then
+
+if.then:
+ %rv_unused = tail call ptr @strcpy(ptr dereferenceable(1) %strcpy_ret_val, ptr dereferenceable(1) %2)
+ br label %return
+
+if.else:
+ %rv_unused_2 = tail call ptr @baz(ptr %arg, ptr %2)
+ br label %return
+
+return:
+ %phi = phi ptr [ %strcpy_ret_val, %if.then ], [ %arg, %if.else ]
+ ret ptr %phi
+}
+
+define ptr @memset_not_to_tailc(ptr %arg, i64 %sz, ptr %ret_val_1, ptr %ret_val_2) {
+; CHECK-LABEL: memset_not_to_tailc:
+; CHECK: ## %bb.0: ## %entry
+; CHECK: movq %rdx, %rax
+; CHECK: testq %rsi, %rsi
+; CHECK: je LBB7_2
+; CHECK: ## %bb.1: ## %if.then
+; CHECK: pushq %rbx
+; CHECK: movq %rcx, %rbx
+; CHECK: movq %rsi, %rdx
+; CHECK: xorl %esi, %esi
+; CHECK: callq _memset
+; CHECK: movq %rbx, %rax
+; CHECK: popq %rbx
+; CHECK: LBB7_2: ## %return
+; CHECK: retq
+entry:
+ %cmp = icmp eq i64 %sz, 0
+ br i1 %cmp, label %return, label %if.then
+
+if.then:
+ tail call void @llvm.memset.p0.i64(ptr align 1 %arg, i8 0, i64 %sz, i1 false)
+ br label %return
+
+return:
+ %phi = phi ptr [ %ret_val_2, %if.then ], [ %ret_val_1, %entry ]
+ ret ptr %phi
+}
+
+declare void @llvm.memcpy.p0.p0.i64(ptr noalias nocapture writeonly, ptr noalias nocapture readonly, i64, i1 immarg)
+declare void @llvm.memset.p0.i64(ptr nocapture writeonly, i8, i64, i1 immarg)
+declare noalias ptr @malloc(i64)
+declare ptr @strcpy(ptr noalias returned writeonly, ptr noalias nocapture readonly)
+declare ptr @baz(ptr, ptr)
>From 72e2a6d62b6bbc498e389ab9a7e551c3e95a70cd Mon Sep 17 00:00:00 2001
From: Antonio Frighetto <me at antoniofrighetto.com>
Date: Sat, 30 Dec 2023 00:25:23 +0100
Subject: [PATCH 2/2] [CGP] Consider arguments and ret values in
`dupRetToEnableTailCallOpts`
Hint further tail call optimization opportunities when the examined
returned value is either the return value of a call instruction, or
a function argument. Moreover, take into account the cases in which
incoming values from phi-nodes, not directly tail call instructions,
may still be simplified.
Fixes: https://github.com/llvm/llvm-project/issues/75455.
---
llvm/lib/CodeGen/CodeGenPrepare.cpp | 57 ++++++++++++++++++-
.../CodeGen/Thumb2/constant-islands-cbz.ll | 18 +++---
llvm/test/CodeGen/X86/tailcall-cgp-dup.ll | 52 +++++++----------
.../X86/live-debug-values-expr-conflict.ll | 16 +++---
4 files changed, 91 insertions(+), 52 deletions(-)
diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
index 5383b15c1c7f5..b360b179a924b 100644
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -2523,7 +2523,8 @@ bool CodeGenPrepare::optimizeCallInst(CallInst *CI, ModifyDT &ModifiedDT) {
}
/// Look for opportunities to duplicate return instructions to the predecessor
-/// to enable tail call optimizations. The case it is currently looking for is:
+/// to enable tail call optimizations. The case it is currently looking for are
+/// simple return of call values, function arguments, or phi nodes as follows:
/// @code
/// bb0:
/// %tmp0 = tail call i32 @f0()
@@ -2580,7 +2581,7 @@ bool CodeGenPrepare::dupRetToEnableTailCallOpts(BasicBlock *BB,
}
PN = dyn_cast<PHINode>(V);
- if (!PN)
+ if (!PN && !isa<Argument>(V) && !isa<CallInst>(V))
return false;
}
@@ -2620,8 +2621,58 @@ bool CodeGenPrepare::dupRetToEnableTailCallOpts(BasicBlock *BB,
// Make sure the phi value is indeed produced by the tail call.
if (CI && CI->hasOneUse() && CI->getParent() == PredBB &&
TLI->mayBeEmittedAsTailCall(CI) &&
- attributesPermitTailCall(F, CI, RetI, *TLI))
+ attributesPermitTailCall(F, CI, RetI, *TLI)) {
TailCallBBs.push_back(PredBB);
+ } else {
+ /// Consider the cases in which the phi value is indirectly produced by
+ /// the tail call, for example when encountering memset(), memmove(),
+ /// strcpy(), whose return value may have been optimized out. In such
+ /// cases, the value needs to be the first function argument.
+ /// @code
+ /// bb0:
+ /// tail call void @llvm.memset.p0.i64(ptr %0, i8 0, i64 %1)
+ /// br label %return
+ /// return:
+ /// %phi = phi ptr [ %0, %bb0 ], [ %2, %entry ]
+ /// @endcode
+ if (PredBB && PredBB->getSingleSuccessor() == BB)
+ CI = dyn_cast_or_null<CallInst>(
+ PredBB->getTerminator()->getPrevNonDebugInstruction(true));
+
+ bool IsIntrinsicOrLibFuncToBeTailCalled = false;
+ if (CI && CI->use_empty() && CI->hasArgument(IncomingVal) &&
+ IncomingVal == CI->getArgOperand(0)) {
+ if (const auto *II = dyn_cast<IntrinsicInst>(CI))
+ switch (II->getIntrinsicID()) {
+ case Intrinsic::memset:
+ case Intrinsic::memcpy:
+ case Intrinsic::memmove:
+ IsIntrinsicOrLibFuncToBeTailCalled = true;
+ [[fallthrough]];
+ default:
+ break;
+ }
+
+ LibFunc LF;
+ Function *Callee = CI->getCalledFunction();
+ if (Callee && TLInfo && TLInfo->getLibFunc(*Callee, LF))
+ switch (LF) {
+ case LibFunc_strcpy:
+ case LibFunc_strncpy:
+ case LibFunc_strcat:
+ case LibFunc_strncat:
+ IsIntrinsicOrLibFuncToBeTailCalled = true;
+ [[fallthrough]];
+ default:
+ break;
+ }
+ }
+
+ if (IsIntrinsicOrLibFuncToBeTailCalled &&
+ TLI->mayBeEmittedAsTailCall(CI) &&
+ attributesPermitTailCall(F, CI, RetI, *TLI))
+ TailCallBBs.push_back(PredBB);
+ }
}
} else {
SmallPtrSet<BasicBlock *, 4> VisitedBBs;
diff --git a/llvm/test/CodeGen/Thumb2/constant-islands-cbz.ll b/llvm/test/CodeGen/Thumb2/constant-islands-cbz.ll
index fc42d4e0e4d8c..6e5cf4d335d94 100644
--- a/llvm/test/CodeGen/Thumb2/constant-islands-cbz.ll
+++ b/llvm/test/CodeGen/Thumb2/constant-islands-cbz.ll
@@ -8,12 +8,11 @@ define ptr @test(ptr returned %this, i32 %event_size, ptr %event_pointer) {
; CHECK-T1-NEXT: .save {r4, lr}
; CHECK-T1-NEXT: push {r4, lr}
; CHECK-T1-NEXT: mov r4, r0
-; CHECK-T1-NEXT: movs r0, #0
-; CHECK-T1-NEXT: str r0, [r4, #4]
-; CHECK-T1-NEXT: str r0, [r4, #8]
-; CHECK-T1-NEXT: str r0, [r4, #12]
-; CHECK-T1-NEXT: str r0, [r4, #16]
-; CHECK-T1-NEXT: mov r0, r4
+; CHECK-T1-NEXT: movs r3, #0
+; CHECK-T1-NEXT: str r3, [r0, #4]
+; CHECK-T1-NEXT: str r3, [r0, #8]
+; CHECK-T1-NEXT: str r3, [r0, #12]
+; CHECK-T1-NEXT: str r3, [r0, #16]
; CHECK-T1-NEXT: cbz r2, .LBB0_2
; CHECK-T1-NEXT: @ %bb.1: @ %if.else
; CHECK-T1-NEXT: bl equeue_create_inplace
@@ -28,11 +27,10 @@ define ptr @test(ptr returned %this, i32 %event_size, ptr %event_pointer) {
; CHECK-T2: @ %bb.0: @ %entry
; CHECK-T2-NEXT: .save {r4, lr}
; CHECK-T2-NEXT: push {r4, lr}
+; CHECK-T2-NEXT: movs r3, #0
; CHECK-T2-NEXT: mov r4, r0
-; CHECK-T2-NEXT: movs r0, #0
-; CHECK-T2-NEXT: strd r0, r0, [r4, #4]
-; CHECK-T2-NEXT: strd r0, r0, [r4, #12]
-; CHECK-T2-NEXT: mov r0, r4
+; CHECK-T2-NEXT: strd r3, r3, [r0, #4]
+; CHECK-T2-NEXT: strd r3, r3, [r0, #12]
; CHECK-T2-NEXT: cbz r2, .LBB0_2
; CHECK-T2-NEXT: @ %bb.1: @ %if.else
; CHECK-T2-NEXT: bl equeue_create_inplace
diff --git a/llvm/test/CodeGen/X86/tailcall-cgp-dup.ll b/llvm/test/CodeGen/X86/tailcall-cgp-dup.ll
index 9241693c1fc82..06fef871f08b7 100644
--- a/llvm/test/CodeGen/X86/tailcall-cgp-dup.ll
+++ b/llvm/test/CodeGen/X86/tailcall-cgp-dup.ll
@@ -188,18 +188,14 @@ return:
define ptr @memset_tailc(ptr %ret_val, i64 %sz) {
; CHECK-LABEL: memset_tailc:
; CHECK: ## %bb.0: ## %entry
-; CHECK: pushq %rbx
-; CHECK: movq %rdi, %rbx
; CHECK: testq %rdi, %rdi
-; CHECK: je LBB4_2
-; CHECK: ## %bb.1: ## %if.then
+; CHECK: je LBB4_1
+; CHECK: ## %bb.2: ## %if.then
; CHECK: movq %rsi, %rdx
-; CHECK: movq %rbx, %rdi
; CHECK: xorl %esi, %esi
-; CHECK: callq _memset
-; CHECK: LBB4_2: ## %return
-; CHECK: movq %rbx, %rax
-; CHECK: popq %rbx
+; CHECK: jmp _memset ## TAILCALL
+; CHECK: LBB4_1: ## %return
+; CHECK: movq %rdi, %rax
; CHECK: retq
entry:
%cmp = icmp eq ptr %ret_val, null
@@ -216,21 +212,15 @@ return:
define ptr @memcpy_tailc(ptr %ret_val, i64 %sz, ptr %src) {
; CHECK-LABEL: memcpy_tailc:
; CHECK: ## %bb.0: ## %entry
-; CHECK: pushq %rbx
; CHECK: testq %rsi, %rsi
; CHECK: je LBB5_1
; CHECK: ## %bb.2: ## %if.then
; CHECK: movq %rsi, %rax
-; CHECK: movq %rdi, %rbx
; CHECK: movq %rdx, %rsi
; CHECK: movq %rax, %rdx
-; CHECK: callq _memcpy
-; CHECK: jmp LBB5_3
-; CHECK: LBB5_1:
-; CHECK: movq %rdx, %rbx
-; CHECK: LBB5_3: ## %return
-; CHECK: movq %rbx, %rax
-; CHECK: popq %rbx
+; CHECK: jmp _memcpy ## TAILCALL
+; CHECK: LBB5_1: ## %return
+; CHECK: movq %rdx, %rax
; CHECK: retq
entry:
%cmp = icmp eq i64 %sz, 0
@@ -251,25 +241,25 @@ define ptr @strcpy_legal_and_baz_illegal(ptr %arg, i64 %sz, ptr %2) {
; CHECK: pushq %r15
; CHECK: pushq %r14
; CHECK: pushq %rbx
-; CHECK: movq %rdx, %r14
+; CHECK: movq %rdx, %rbx
; CHECK: movq %rsi, %r15
-; CHECK: movq %rdi, %rbx
+; CHECK: movq %rdi, %r14
; CHECK: movq %rsi, %rdi
; CHECK: callq _malloc
; CHECK: testq %r15, %r15
-; CHECK: je LBB6_2
-; CHECK: ## %bb.1: ## %if.then
+; CHECK: je LBB6_1
+; CHECK: ## %bb.2: ## %if.then
; CHECK: movq %rax, %rdi
-; CHECK: movq %r14, %rsi
-; CHECK: movq %rax, %rbx
-; CHECK: callq _strcpy
-; CHECK: jmp LBB6_3
-; CHECK: LBB6_2: ## %if.else
-; CHECK: movq %rbx, %rdi
-; CHECK: movq %r14, %rsi
+; CHECK: movq %rbx, %rsi
+; CHECK: popq %rbx
+; CHECK: popq %r14
+; CHECK: popq %r15
+; CHECK: jmp _strcpy ## TAILCALL
+; CHECK: LBB6_1: ## %if.else
+; CHECK: movq %r14, %rdi
+; CHECK: movq %rbx, %rsi
; CHECK: callq _baz
-; CHECK: LBB6_3: ## %return
-; CHECK: movq %rbx, %rax
+; CHECK: movq %r14, %rax
; CHECK: popq %rbx
; CHECK: popq %r14
; CHECK: popq %r15
diff --git a/llvm/test/DebugInfo/X86/live-debug-values-expr-conflict.ll b/llvm/test/DebugInfo/X86/live-debug-values-expr-conflict.ll
index afce27ee4abb9..2769d39fa54aa 100644
--- a/llvm/test/DebugInfo/X86/live-debug-values-expr-conflict.ll
+++ b/llvm/test/DebugInfo/X86/live-debug-values-expr-conflict.ll
@@ -24,18 +24,18 @@
; one in the block two, and none in block three.
; CHECK: ![[BAZVAR:[0-9]+]] = !DILocalVariable(name: "baz",
; CHECK-LABEL: bb.0.entry:
-; CHECK: DBG_VALUE {{[0-9a-zA-Z$%_]*}}, $noreg, ![[BAZVAR]],
+; CHECK: DBG_VALUE {{[0-9a-zA-Z$%_]*}}, $noreg, ![[BAZVAR]],
; CHECK-SAME: !DIExpression()
; CHECK-LABEL: bb.1.if.then:
-; CHECK-LABEL: bb.2.if.else:
-; CHECK: DBG_VALUE {{[0-9a-zA-Z$%_]*}}, $noreg, ![[BAZVAR]],
+; CHECK-LABEL: bb.3.if.else:
+; CHECK: DBG_VALUE {{[0-9a-zA-Z$%_]*}}, $noreg, ![[BAZVAR]],
; CHECK-SAME: !DIExpression()
-; CHECK: DBG_VALUE_LIST ![[BAZVAR]],
-; CHECK-SAME: !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_plus_uconst, 1, DW_OP_stack_value)
-; CHECK-SAME: {{[0-9a-zA-Z$%_]*}}
-; CHECK-LABEL: bb.3.if.end:
+; CHECK: DBG_VALUE_LIST ![[BAZVAR]],
+; CHECK-SAME: !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_plus_uconst, 1, DW_OP_stack_value)
+; CHECK-SAME: {{[0-9a-zA-Z$%_]*}}
+; CHECK-LABEL: bb.2.if.then:
; CHECK-NOT: DBG_VALUE
-; CHECK-NOT: DBG_VALUE_LIST
+; CHECK-NOT: DBG_VALUE_LIST
declare void @escape1(i32)
declare void @escape2(i32)
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