[clang] [llvm] [SystemZ] Add SP alignment to the DataLayout string. (PR #176041)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-systemz

Author: Jonas Paulsson (JonPsson1)

<details>
<summary>Changes</summary>

Add '-S64' to the SystemZ datalayout string, to avoid overalignment of stack objects.

This changes 25 files on SPEC over 5 benchmarks, with fewer cases of runtime-alignment (NILL instructions).

@<!-- -->uweigand @<!-- -->nikic 

---
Full diff: https://github.com/llvm/llvm-project/pull/176041.diff


3 Files Affected:

- (modified) clang/test/CodeGen/target-data.c (+3-3) 
- (modified) llvm/lib/TargetParser/TargetDataLayout.cpp (+3) 
- (added) llvm/test/CodeGen/SystemZ/stack-align.ll (+17) 


``````````diff
diff --git a/clang/test/CodeGen/target-data.c b/clang/test/CodeGen/target-data.c
index e95079490bd3c..ee8e45511720c 100644
--- a/clang/test/CodeGen/target-data.c
+++ b/clang/test/CodeGen/target-data.c
@@ -207,11 +207,11 @@
 // RUN: FileCheck %s -check-prefix=SYSTEMZ
 // RUN: %clang_cc1 -triple s390x-unknown -target-cpu z13 -target-feature +soft-float -o - -emit-llvm %s | \
 // RUN: FileCheck %s -check-prefix=SYSTEMZ
-// SYSTEMZ: target datalayout = "E-m:e-i1:8:16-i8:8:16-i64:64-f128:64-v128:64-a:8:16-n32:64"
+// SYSTEMZ: target datalayout = "E-S64-m:e-i1:8:16-i8:8:16-i64:64-f128:64-v128:64-a:8:16-n32:64"
 
 // RUN: %clang_cc1 -triple s390x-unknown -target-cpu z13 -o - -emit-llvm %s | \
 // RUN: FileCheck %s -check-prefix=SYSTEMZ-VECTOR
-// SYSTEMZ-VECTOR: target datalayout = "E-m:e-i1:8:16-i8:8:16-i64:64-f128:64-v128:64-a:8:16-n32:64"
+// SYSTEMZ-VECTOR: target datalayout = "E-S64-m:e-i1:8:16-i8:8:16-i64:64-f128:64-v128:64-a:8:16-n32:64"
 
 // RUN: %clang_cc1 -triple s390x-none-zos -target-cpu z10 -o - -emit-llvm %s | \
 // RUN: FileCheck %s -check-prefix=ZOS
@@ -219,7 +219,7 @@
 // RUN: FileCheck %s -check-prefix=ZOS
 // RUN: %clang_cc1 -triple s390x-none-zos -target-cpu z13 -o - -emit-llvm %s | \
 // RUN: FileCheck %s -check-prefix=ZOS
-// ZOS: target datalayout = "E-m:l-p1:32:32-i1:8:16-i8:8:16-i64:64-f128:64-v128:64-a:8:16-n32:64"
+// ZOS: target datalayout = "E-S64-m:l-p1:32:32-i1:8:16-i8:8:16-i64:64-f128:64-v128:64-a:8:16-n32:64"
 
 // RUN: %clang_cc1 -triple msp430-unknown -o - -emit-llvm %s | \
 // RUN: FileCheck %s -check-prefix=MSP430
diff --git a/llvm/lib/TargetParser/TargetDataLayout.cpp b/llvm/lib/TargetParser/TargetDataLayout.cpp
index b8c3b4325558c..b985c1eec4244 100644
--- a/llvm/lib/TargetParser/TargetDataLayout.cpp
+++ b/llvm/lib/TargetParser/TargetDataLayout.cpp
@@ -357,6 +357,9 @@ static std::string computeSystemZDataLayout(const Triple &TT) {
   // Big endian.
   Ret += "E";
 
+  // The natural stack alignment is 64 bits.
+  Ret += "-S64";
+
   // Data mangling.
   Ret += getManglingComponent(TT);
 
diff --git a/llvm/test/CodeGen/SystemZ/stack-align.ll b/llvm/test/CodeGen/SystemZ/stack-align.ll
new file mode 100644
index 0000000000000..d7f6b1e8a46f2
--- /dev/null
+++ b/llvm/test/CodeGen/SystemZ/stack-align.ll
@@ -0,0 +1,17 @@
+; RUN: opt < %s -mtriple=s390x-unknown-linux-gnu -mcpu=z16 -S -passes=infer-alignment \
+; RUN:   2>&1 | FileCheck %s
+;
+; Test that the alignment of the alloca is not increased beyond the stack
+; alignment of 8 bytes.
+
+declare void @foo(ptr)
+
+define void @f1(<4 x i64> %Arg) {
+; CHECK-LABEL: define void @f1
+; CHECK-NEXT:    %param = alloca <4 x i64>, align 8
+; CHECK-NEXT:    store <4 x i64> %Arg, ptr %param, align 8
+  %param = alloca <4 x i64>, align 8
+  store <4 x i64> %Arg, ptr %param, align 8
+  call void @foo(ptr %param)
+  ret void
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/176041