Use the LLVM option NoTrapAfterNoreturn

majaha · majaha · commit 6fa99de1b077 · 2023-04-18T12:24:22.000+01:00
Use this LLVM option: https://llvm.org/doxygen/classllvm_1_1TargetOptions.html#acd83fce25de1ac9f6c975135a8235c22 when TrapUnreachable is enabled. This prevents codegenning unnecessary double-traps in some situations.
diff --git a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
@@ -419,6 +419,8 @@ extern "C" LLVMTargetMachineRef LLVMRustCreateTargetMachine(
     // it prevents control flow from "falling through" into whatever code
     // happens to be laid out next in memory.
     Options.TrapUnreachable = true;
+    // But don't emit traps after other traps or no-returns unnecessarily.
+    Options.NoTrapAfterNoreturn = true;
   }
 
   if (Singlethread) {

Original file line number	Diff line number	Diff line change
`@@ -419,6 +419,8 @@ extern "C" LLVMTargetMachineRef LLVMRustCreateTargetMachine(`
`419`	`419`	`// it prevents control flow from "falling through" into whatever code`
`420`	`420`	`// happens to be laid out next in memory.`
`421`	`421`	`Options.TrapUnreachable = true;`
	`422`	`+ // But don't emit traps after other traps or no-returns unnecessarily.`
	`423`	`+ Options.NoTrapAfterNoreturn = true;`
`422`	`424`	`}`
`423`	`425`
`424`	`426`	`if (Singlethread) {`